Front vents not blowing?? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Front vents not blowing??


dustinmaddox
03-21-2009, 03:33 AM
I have 2004 Trailblazer and had the battery replaced two days ago. After I drove away from NTB my AC, which was working fine prior to battery replacement, will not blow out of front vents When AC "mode" is set to blow out front vents it will only blow at my feet and windsheild. Seems to be cooling well, except air no longer comes out front vents. The NTB people said that in GM cars the system sometimes needs to reset itself and it could take a few days or more and will work like it should when it resets. NTB said the dealership would tell me the same thing. What should I do?

the roadie
03-21-2009, 02:27 PM
Yes. After battery replacement, the HVAC system needs to recalibrate all the mode, temp, and recirculate actuators. Those are little motors with feedback circuits, and they need to be undisturbed when they're in the middle of recalibrating. If you hit a control button or change the temp in the first 1-2 minutes after you start the car again, the calibration will silently fail, and it won't tell you except by blowing the wrong temp air where you don't want it. And more annoyingly - it won't even attempt the recalibration process again. It just gives up.

Simple fix. You can pull the battery off again for a few minutes, or easier: pull HVAC B fuse #36 in the rear fuse block (under the rear seat - driver's side) for 2 minutes. Then put it back in with the ignition off. Then turn the key to the RUN position, but don't start the engine. Don't touch the HVAC controls for 2 minutes, and you should hear the actuators and blower motor going through all the modes and speeds. Then it should be happy and you can drive away.

dustinmaddox
04-07-2009, 12:22 AM
This did not fix the problem. Do you or anyone else know what else I can try?? Anything is a start!!

the roadie
04-07-2009, 12:58 AM
Did the actuators go through their motions and make noises during the recalibration sequence? This is a very important question.

Your mode actuator could have died as a coincidence. The problem is definitely a failure of the mode actuator or the HVAC control box or the wiring between the two.

There are three actuators on the driver's side of the HVAC plenum behind the dashboard covers. The mode actuator is the middle one of the three. If you can disassemble your dash and look at it while it goes through a recalibration process, you can conclude whether or not it's dead. Want to be digging into your dash like that, or just pay a dealer to diagnose it for you? We can talk you through as much of this as you want, or as little.

dustinmaddox
04-07-2009, 01:40 AM
Yes it does make the noises and sound like it is going to work, however, I am not seeing ANY results.

Dustin03
04-25-2009, 07:45 PM
I'm having the same trouble with a 2006 Envoy XL. If you can teach me how to take the dash apart, I have already bought the new actuator.

Thanks for the help!

jmajtyka
04-30-2009, 11:42 AM
Hello I have had the same problem with my 2004, The actuator that controlled the air for the vents stopped working after a little investigating and attempting the re-calibration process by pulling the fuse I found the actuator would attempt to reposition it self, long story short ended up being the encoder in the unit went bad replace the actuator and re-calibrated working fine now I will be glad to post pics of where the dash needs to be taken apart and where it is located, not all that easy of thing to do but better then paying the stealer,

BTW I got a brand new ACDelco actuator on ebay 25.00 look around there if you need one.

Jim

Ray Dockrey
04-30-2009, 01:51 PM
If you do a search on here you will find all the info you need for changing out the mode door actuator including a how-to with pics.

dustinmaddox
04-30-2009, 02:04 PM
Yes if you could show me where to take the dash apart and what to buy... I would be so grateful!!

jmajtyka
04-30-2009, 02:30 PM
Dustin Ill be glad to help you out Ill take some pictures of what needs to come out this after noon, as far as getting the Actuator you will have to do a search on ebay or online merchants, I found mine on ebay,

Ray Dockrey
04-30-2009, 02:34 PM
Here you go.

http://forums.trailvoy.com/showthread.php?t=40235

jmajtyka
04-30-2009, 02:40 PM
Thank you saves me from getting the camera out,

Jim

Dustin03
04-30-2009, 02:59 PM
Here you go.

http://forums.trailvoy.com/showthread.php?t=40235

Umm... Can I get a little more help? I've seen that thread before, and it doesn't tell me anything about how to take the dash apart. Maybe someone can explain how you "take the lower dash panels off?"

I don't mean to sound impatient, but I've been messing with this f***ing thing for weeks. :suicide:

jmajtyka
04-30-2009, 03:39 PM
Ok what you need to do is remove the knee bolster, just Below the steering column, first thing is to remove two 7mm blots that hold on the obd connector, then you will follow the black cover towards the steering wheel, Remove 2 more 7mm bolts Now care fully remove the black trim, Once that is removed you can now remove 4 7mm bolts that hold the knee bolster, two below the steering wheel one left and right side, and the other 2 are on the bottom of it towards the gas petal, with those removed it should make it easy to get to the actuator as shown in the pics on the other post, I fount the best ay to get to it was to lay on my back, mostly feel to remove it, when it stops raining I ll get out there and take some pics for you of the location for the dash bolts

Jim

the roadie
04-30-2009, 03:43 PM
And between every bolt removed, remember to bellow at the required beer wench for a delivery. Take the bottle in your right hand, assuming you're right handed, tilt it smartly towards your lips, and enjoy. After four bolts and four beers, you may feel the need for a relief break. Using your right hand, assuming you're right handed .........

Dustin03
04-30-2009, 04:17 PM
Ha ha! Thanks for the help guys, but is that it? I had that panel off last time, and the actuator was in the center section of the dash, behind the radio and HVAC controls where I couldn't get to it. What's the trick? Going by the pictures I've seen I know that I'm looking at the right spot, but I can't see the actuator I need to replace because it's behind the dash panel still. Do I have to take the center console out?

jmajtyka
04-30-2009, 04:24 PM
No you do not need to remove the center dash panel, all is done from drivers side, have to reach up there you can sorta see it but removing is done by feeling for the bolts on the actuator,

Just trying to help you out with it,

Jim,

jmajtyka
04-30-2009, 04:27 PM
this is from the drivers side showing the actuator,

Dustin03
04-30-2009, 05:21 PM
Alright, thanks guys. I'll have to give it another shot in the next couple days. Finals are kicking my a** right now, so this project is on hold for the moment. I'll let you know how it went. :tiphat

TheCOBRA
05-12-2009, 05:16 PM
Did the actuators go through their motions and make noises during the recalibration sequence? This is a very important question.

Your mode actuator could have died as a coincidence. The problem is definitely a failure of the mode actuator or the HVAC control box or the wiring between the two.

There are three actuators on the driver's side of the HVAC plenum behind the dashboard covers. The mode actuator is the middle one of the three. If you can disassemble your dash and look at it while it goes through a recalibration process, you can conclude whether or not it's dead. Want to be digging into your dash like that, or just pay a dealer to diagnose it for you? We can talk you through as much of this as you want, or as little.

Will I have to remove the seat to get to the rear fuses in my 2004 trailblazer? If you would tell me how to get to them I would appreciate that.:thx

the roadie
05-12-2009, 05:59 PM
Will I have to remove the seat to get to the rear fuses in my 2004 trailblazer? If you would tell me how to get to them I would appreciate that.:thxI highly recommend reading the Owner's Manual cover to cover whenever you get a new vehicle. If you didn't get one, trailvoy has PDF copies of almost all of them under the Resources pull-down tab above.

I could just give you the answer as to how many and what size bolts it requires to remove the rear seats, but I think it would be illuminating for you to read it for yourself in the manual. Sorry to be a pill, but it's important that you learn how to fish instead of just being given a fish. :thumbsup:

Hint: with a short wheelbase vehicle the jack is also under the rear seat.

TheCOBRA
05-14-2009, 01:13 PM
Yes. After battery replacement, the HVAC system needs to recalibrate all the mode, temp, and recirculate actuators. Those are little motors with feedback circuits, and they need to be undisturbed when they're in the middle of recalibrating. If you hit a control button or change the temp in the first 1-2 minutes after you start the car again, the calibration will silently fail, and it won't tell you except by blowing the wrong temp air where you don't want it. And more annoyingly - it won't even attempt the recalibration process again. It just gives up.

Simple fix. You can pull the battery off again for a few minutes, or easier: pull HVAC B fuse #36 in the rear fuse block (under the rear seat - driver's side) for 2 minutes. Then put it back in with the ignition off. Then turn the key to the RUN position, but don't start the engine. Don't touch the HVAC controls for 2 minutes, and you should hear the actuators and blower motor going through all the modes and speeds. Then it should be happy and you can drive away.

--------------------------------------------------------------------------------

At first the vents would not work after battery replacement. Now only the vents work. But get this, they are only blowing out hot air. It won't even change to any of the other settings (floor, defrost). The A/C will not come on either. Can someone please help a fella out?

maneuen
05-20-2009, 10:11 PM
2003 Trailblazer with the same problem - I've tried resetting the fuse - when I turn the ignition back to on - the ac defaults to auto and blows - if I turn the a/c off - I can then here it trying to reset (although the blowers never turn off). finally when I first start the car - if blows through the vents for 2 seconds and then goes to the floor and dash.

Does this still sound like the HVAC mode actuator? or is there something else to check when I have it all apart?

the roadie
05-20-2009, 10:26 PM
When you reset the fuse and turn the ignition back on, are you leaving all controls untouched for 90 seconds? It's the only way to allow the reclaibration process to compete on its own. If you are leaving it alone, then your control module sounds bad. You should be able to pay the dealer to confirm it.

Can you fill out your profile and confirm you have the digital system?

maneuen
05-20-2009, 11:07 PM
When you reset the fuse and turn the ignition back on, are you leaving all controls untouched for 90 seconds? It's the only way to allow the reclaibration process to compete on its own. If you are leaving it alone, then your control module sounds bad. You should be able to pay the dealer to confirm it.

Can you fill out your profile and confirm you have the digital system?

Yes I have the digital system (updated profile), and yes I left it alone for 90 seconds - in the "run" (but not started) position. In that scenario, it simply reverts to "auto" - it immediately blows through the vents for a couple seconds and then goes to the dash and floor and stays - no further cycling.

If it turn the a/c off and then turn the key to "run" I can hear the actuators cycling - but no change in the result

so is the control module the acutal digital display in the dash, or is it something else?

the roadie
05-20-2009, 11:58 PM
It's the display in the dash and the knobs and buttons. Not hidden deeper. I think that's bad if it won't reset theactuators properly. See if you can find a friend to swap with before you buy one.

mxracer46x
05-31-2009, 04:41 PM
I have a 2003 trailblazer and had same problem with no air coming from dash vents. I tried the fuse trick with no luck. I'm a little short on cash and cant afford the new mode door acuator from dealer $97. I decided to try to open door myself so i could have cold air out of the dash vents.

After you take off panels and plastic floor vent duct pipe look up and find the correct mode door acuator. Look on the side with the sticker that has letters H,L and some numbers on it. In the center of part you will see a round hole with a metal piece that has two notches. Find something that fits in the notches of that hole, like a screwdriver. I didn't have a screwdriver that size so i used an old flat nosed butter knife that fit almost perfect. You might need to modify something to fit if you don't have anything. Stick your tool in hole and turn about a quarter turn. It was a little difficult to turn but you will feel and hear the mode door open. Next unplug the wire harness that goes to that acuator. I put black tape over end of wire harness just to be on the safe side. Reinstall your plastic floor duct vent and panels. This took me about 10-15 minutes to do.

I did try to leave the wire harness plugged in but when i restarted vehicle the door closed. The dash vents will blow now all the time unless you turn off blower fan or turn off dash vents on the dash where the air deflector is.

I'm not a auto mechanic and do not know if what i did will cause any problems to my vehicle or yours if you try this. I was at a point of go without dash vents or pay for a new part, so i figured i had nothing to lose if i did break the mode door acuator. just be sure you are trying to open the correct one. So far i have not had any problems and don't think i will. Try at your own risk.

Good Luck and Thank You to all who have posted here with problems and solutions that have helped me out with my trailblazer

Enzymaticracer
06-11-2009, 08:56 PM
Hi Everyone.

I found this forum after doing some searching on how to fix my ventilation system problems. I just had some service done to my 2003 Trailblazer LT, and in the process they broke the leads on my battery, so they replaced it. When I got it back, my ventilation wasn't working, but rather than take it back to that place for them just to screw up my truck even more and still take tons of my money(long story...), I decided to try and fix it myself first.

Thats when I stumbled onto this thread, and thought I'd sign up.

So far, I have tried pullling the fuse, leaving it out for 5 minutes, then putting my truck in to "run" without actually starting it, and letting it run for 5 minutes without touching anything.

I'm still having the problem of not getting anything air out of my dash vents. It only comes out of the floor vents, the windshield vent (when defrost is enabled), or the two vents pointed at the driver and passenger windows.

Would the next logical step be to replace the mode actuator? I don't actually have too many tools, would this step be possible at all with just an adjustable wrench? I can always run to costco and pick up a ratcheting tool set for relatively cheap if necessary.

Anyways, thanks everyone for all of the information that you have provided.

the roadie
06-11-2009, 09:13 PM
You've done the right stuff, and now need to change the mode actuator. Not possible with only an adjustable wrench. Got any buddies with tools you can bribe with beer to help?

Enzymaticracer
06-11-2009, 09:18 PM
You've done the right stuff, and now need to change the mode actuator. Not possible with only an adjustable wrench. Got any buddies with tools you can bribe with beer to help?

Sadly, not in the area, closest would be about 5 hours away. Probably not a bad idea for me to pick up the tools to do this anyway... I guess I'll start looking around for places to order a new actuator.

Thanks to everyone for all of the help again.

TheCOBRA
06-12-2009, 09:59 AM
Hey folks,

I almost got my 04 Trailblazer's a/c working. I replaced the control module and I now have cold a/c. But there still isn't anything coming from the dash vents. Does anyone have the part # for the actuator? Thanks for your help.:thumbsup:

the roadie
06-12-2009, 11:23 AM
ACDELCO #15-72972
GM #89018375

I should just put these in my signature, I post 'em so often. :rolleyes:

Enzymaticracer
06-12-2009, 06:58 PM
ACDELCO #15-72972
GM #89018375

I should just put these in my signature, I post 'em so often. :rolleyes:

Is there a good place to order these from?

The parts places I'm finding that have either or those are charging between ~$90 to ~$120... hoping for a little better... I'll keep looking, but if thats what it takes, I'd like some input on the best place to order from before I order...


Thanks for all your help.

So Anyways, I just went down to my truck to take a look at everything. This time I removed all of the panel and the ducting while I had the fuse pulled (I'm a big guy... 6'3" and 240 lbs, so it helped me a lot to remove as many pieces of stuff that was easy to remove. Anyways, after I stuck the fuse back in and sat and watched the actuators, there was definitely one that did not rotate at all.

I tried unplugging that actuator and moving it with a screwdriver while it was still attached, but I couldn't get it to budge. I think this is pretty good confirmation that that is the piece that is broken. I'll see if I can't go get some ratchets to take the actuator off this weekend and see if I can move it once I get it removed from my truck. I left it unplugged for now just because there's no reason to plug it back in if it isn't going to move.

Thanks for all of the help guys.

the roadie
06-12-2009, 07:48 PM
Rockauto.com
parts4chevys.com
Amazon vendors
Ebay
junkyards (car-parts.com)

I haven't been seeing these too much cheaper than you're finding, except for the odd bargain on Ebay. I posted in another thread - I'm very disturbed by the number of failures in these things as our vehicles age, and would like to analyze a few to see if there's a common root cause. Anybody with a bad actuator who would like to send it to me at my expense, please PM me.

Roamingdoc
06-14-2009, 09:42 PM
Here's a bit of background -
http://forums.trailvoy.com/showthread.php?t=58172

Basically, undid battery the 'wrong' way (did + side first, got one spark) in removing the PCM for PCMforless (wonderful results so far). :duh:

Have "dual mode" '02 LTZ TBlzr (4whldrv) and ONLY the left side is having an issue. No outside air and no 'A/C' -

I 'have not' yet removed the HVAC-B fuse from under the back seat (ahh, do I have to remove the 'gas tank' first? Only kidding, but I know how this subject has been a problem for many) but did the 'remove - battery cable, 30 minutes or a bit more, reconnect, key to RUN for 90 seconds but NO touching anything. No change in symptoms.

The left side WILL SWITCH from upper or dash vents to 'floor' on the problemed side... but will not receive "full" fan results (in other words, not much change in air flow from slow to fast fan) - the air coming out is warm even when the 'controls' indicate outside air or A/C.

Are there more 'actuators' for DUAL mode systems than one with a single set of controls? Is there, are there more fuses - I checked the owner's manual and don't see any more than schematics indicate here at TV - is there something DIFFERENT to do with DUAL mode fixes? :worried:

Many thanks... I leave for a long road trip and this just happened. May try the 'get vent open' and disconnect trick mentioned in this thread as I really want something besides 'warm' air coming out onto me as I drive 5000 miles.:sadcry:

Appreciate the help.

the roadie
06-14-2009, 10:11 PM
My goodness, why would you think I'm about to whap somebody all the time? :no: :duh:

You've the innocent victim here. Of GM's (actually Delphi/Delco) marginal design.

All trailvoys have DUAL controls. It's just some are slide temp controls (manual or analog) and some are rotary controls (automatic or digital).

All systems have the same number of actuators.

******************************************

Your problem may be with the driver's side TEMP actuator. Fiddling with the mode and temp controls may let you figure out which. Hope it's not both temp and mode.

Pulling the HVAC-B fuse for a minute is just a faster way to force a reset of the system without costing the PCM its adaptive memory settings and making the engine and transmission drive like crap for an hour after you reconnect it.

And pulling the battery plus side first can't be the root cause of any of this. Pulling the negative battery cable is ONLY recommended because then the wrench you use is automatically grounded and can't cause a spark if you accidentally hit it into the engine compartment sheet metal. When either the positive or negative connector leaves the battery there will always be a small spark because of the residual current drain by modules (like the BCM and the liftgate modules, waiting for a remote keyfob unlock command)

Roamingdoc
06-15-2009, 12:19 AM
Great graphic.
I leave on Tuesday AM so won't have time to do much. The temp controls do 'not' change anything on the left (effected) side. They do work splendidly on the passenger side.
Selecting 'floor' in the mode does shift the 'small' amount of air coming on the left side to the floor vents but it is warm air only even when A/C is selected.

I was hoping there was some 'fuse' that could've blown which would take the left side out of the equation but it doesn't sound like that is possible. I'll try pulling the HVAC-B fuse (vs. disconnecting the battery - AND YOU are so right, disconnecting the battery makes thing run ragged for a while - when I first did that I thought I lost the PCMforLess work but not the case).
Just the wrong time for this to happen. :hopeless
When I get home I'll have to pull the lower dash stuff and see if I can make head or tails out of this stoppage. I've heard there is some 'special' (means money to chevy ;^) tool to pull the 'actuator' out?

Thanks again!!!

Enzymaticracer
06-15-2009, 09:19 AM
Rockauto.com
parts4chevys.com
Amazon vendors
Ebay
junkyards (car-parts.com)

I haven't been seeing these too much cheaper than you're finding, except for the odd bargain on Ebay. I posted in another thread - I'm very disturbed by the number of failures in these things as our vehicles age, and would like to analyze a few to see if there's a common root cause. Anybody with a bad actuator who would like to send it to me at my expense, please PM me.

Thanks for all of the help Roadie.

I went and bought a nice set of ratchets and sockets this weekend so I could do some more work.

Anyways, I was able to pull the mode actuator out (man... talk about a tight fit... it's tough for me to just get a hand up there...).

I decided I'd pull it apart to take a quick look. All of the teeth on the gears looked ok. I tried rotating some of them a little bit, and everything looked like it worked ok. It felt like it started turning a little bit easier after I jiggled them a little bit, so since I don't have a new actuator yet, I went ahead and put it back on.

While the actuator was off, I reached up to the empty spot and moved the the lever around a little bit... I would pull it down, but it would always move back up to the top (I'm guessing because of a weight on the other side), so I ended up just leaving it in the top position while I put the actuator back on. I ended up getting frustrated to no end trying to get the one screw in, so I just left it off and tightened the one I could get it down nicely. I figured since I'm going to be replacing the part theres no need to completely secure it. I did reconnect the actuator and reset the system so I could see what happens.

The gear did turn one direction, but then it stopped and never started moving the other direction like the other actuator, so I'm guessing the gear is slipping on its axle or something.

In any case, I'm now getting air out of my front vents, so I'm pretty happy. This means I hopefully can wait a little longer to buy the part since I just spent the $80 on the new toolset (which surprisingly has a 5.5mm socket).

Thanks for all your help again roadie.

tfg4tb
06-24-2009, 08:37 PM
I highly recommend reading the Owner's Manual cover to cover whenever you get a new vehicle. If you didn't get one, trailvoy has PDF copies of almost all of them under the Resources pull-down tab above.

I could just give you the answer as to how many and what size bolts it requires to remove the rear seats, but I think it would be illuminating for you to read it for yourself in the manual. Sorry to be a pill, but it's important that you learn how to fish instead of just being given a fish. :thumbsup:

Hint: with a short wheelbase vehicle the jack is also under the rear seat.

The seat flips up super easy.

lglindfw
08-06-2009, 05:15 PM
First ... what a great site. I've learned a bundle just browsing it!

Second ... I've been bitten by the actuator bug which seems to be pretty common for the 2004 Trailblazer. I had to replace the battery and when I started it back up ... not dash vents working.

I've removed the dash and pulled the actuator that wasn't working. I popped it open and messed with the gears a bit (didn't touch the big white and blue one though). When I reinstalled it the air started coming from the dash vents ... but not the floor vent. I can live with that but I was wondering why that would have happened (did I have the calibration wrong) and what other problems it may cause.

Also, I wanted to verify that all these actuators (mode, driver/pass temp and defrost actuators) are the same part number. Is that true?

I've found one for a 04 GMC ENVOY XL A/C Vacuum Actuator ACDELCO 1573596 which says it replaces the 89018675 but I noticed different part numbers in some of the other posts. I have a 2004 Trailblazer.

Any help would be greatly appreciated. Thanks.

the roadie
08-06-2009, 05:28 PM
Putting a bad actuator back on to lock the door in a useful position isn't harmful, and might be a good short-term workaround. Somehow, messing with the gears changed the preset "rest" position of the actuator, which still fails calibration. No worries there.

Oddly, the actuators are all different. Could have been designed the same for part number minimization, but nooooooooooo.

Your part number on Ebay has "Vacuum" in the description? What a hoot. No vacuum powering up our totally electronic vehicle. :cool: Rockauto goofed.

I'm not sure I'd trust that part number if you didn't see it on the compnine site or posted here as a good one.

Peruse this page:
http://www.compnine.com/index.php?u=1&year=2004&artnbr=TS09-106&artsfx=NULL&supplgroup=NULL&catcode=56S&modelcode=T&makecode=LC&modelseries=NULL&uid=1&modelid=7132&capuid=1&majorgroup=09&grouptype=B

http://www.compnine.com/largeimg/060306TS09-106.gif

lglindfw
08-06-2009, 06:58 PM
ACDELCO #15-72972
GM #89018375

I should just put these in my signature, I post 'em so often. :rolleyes:

I found this part number at rockauto.com for $97, but it says its a "ACTUATOR,TEMP VLV LEFT HAND" which sounds like a temperature actuator for the driver side.

My problem is with no air coming through the dash vents so I figured I needed a mode actuator.

Rockauto.com has an ACDELCO Part # 1573596 (89018675) ACTUATOR, MODE VLV w/A/C FRT AUTO/AUX CONT(CJ2) for $40.

Any help would be grealtly appreciated. I need to make sure I'm buying the right actuator and if it cost's $40 instead of $97 ... that would be even better.

mzobrist
09-30-2009, 11:24 PM
Was the 89018675 part number the correct part number? I am looking at doing this too. A/c vents just stopped blowing, only can get thru the floor or dash.

BigJob
10-02-2009, 09:51 AM
I posted a thread about this recently and got no response lol.
But I just recently had this issue, after installing my CD player, A/C works fine but only comes out at feet or defrost vents, no dash. Mode actuator?

ALSO: Fan Speeds (Off, 1, 2, 3, 4, 5) Nothing happens until I turn it to 3. In other words, 1 and 2 do not work. This is the blower motor resistor correct?

the roadie
10-02-2009, 11:57 AM
Yes to both questions.

BigJob
10-02-2009, 04:26 PM
I went ahead and replaced the resistor today, fixed the fan speed issue :D

So what is the exact part number I should search for for that actuator?

mzobrist
10-02-2009, 09:53 PM
I'm pretty sure this is it:
ACDELCO Part # 1573596 {#89018675}

BigJob
10-04-2009, 03:12 PM
Thanks!

Enzymaticracer
10-27-2009, 03:24 PM
So I finally ordered a new actuator from rockauto, which came in this past weekend.

This Part,

ACDELCO 15-72972

Did not come with it's own arm, so I pulled the arm out of the old one and put it into the new part.

Here's my problem, after wrestling with the freaking screws for god knows how long, plugging the actuator in, pulling/plugging the fuse to reset, I'm still not getting any air out of my floor vents.

It sounds like the actuator is trying to turn, and I am hearing a clicking sound during the calibration stage (it isn't continuously turning). The first time I did it, the actuator moved, and then never started turning the other direction, so I thought I may have not had the arm in the correct place. So I took the cover off the actuator so that I could remove a gear to allow my to move the arm to the other side of the arc, replaced everything again, and basically the same result.

What now? I thought about trying to reposition the gear that the actuator is supposed to turn, but it always swings back into the upper position, and there's no way I'm going to get that actuator in place before it swings back... so what do I do?

Thanks for any help

the roadie
10-27-2009, 03:32 PM
When you disassembled the actuator, did you disturb the relationship of the motor side of the gear train to the blue position feedback potentiometer? I did that when I was analyzing my actuator problem (I was trying to repair the one I had instead of buying a new one - and it worked), but getting it back in the right relationship took a LONG time and I reverse engineered how it was supposed to work.

You can try to keep the vehicle side of the system from moving for a few seconds with chewing gum or plumber's putty.

Enzymaticracer
10-27-2009, 03:46 PM
Well,

The large final gear that actually rotated the arm appeared to have two copper strips hanging down from the bottom that contacted two copper strips spanning the circuit board below that gear (much like how the old slot cars used to get their power).

I did notice that after the first attempt, those copper strips had actually moved past the edge of the circuit board, and were preventing the gear from moving in the other direction. I then had to pull up on that gear enough to have those strips clear the board, That is when I decided to try and reposition the gear so that those copper strips started at the other end of the circuit board during the calibration cycle. The only other piece I touched was the next gear down the line (which I had to remove to pull the large gear up).

I haven't removed the actuator to take a look at it yet because it was already dark outside by the time I got to that point, and I was frustrated. May try to take it back off this weekend if I have time and it isn't raining...

Enzymaticracer
11-15-2009, 05:53 PM
Anyways,

so today ended up being great weather, so I figured I would give this fix another shot.

After about 4 hours of trial and error, I'm back to having air come out of just the floor vents, which considering it is cooling down, where it needs to be.

Anyways, here's the weird part.

It feels like I have the actuator arm and vehicle side arm in the proper places. The actuator arm has a notch in it where an extra bar on the vehicle arm slides in to place, and I can feel it when I put the actuator back in place and screw it in. Problem is, after pulling the fuse, and restarting the calibration, I get air through the front vents, then it moves to the floor, but then it stays there. Selecting the front vents in the system does not move the actuator back to the up position.

HOWEVER, if I pull the fuse again, and start the calibration over, I will get air through the top vents (with none out of the foot vents) during the calibration, but it will not go back up. I repeated this several times, and air would come through the front vents every time before moving to my feet for good.

Any idea's as to what is going on here?:confused::confused::confused:

Enzymaticracer
11-19-2009, 12:07 PM
I've been thinking about this some more,

Do I just need to buy another actuator and get it put in without ever opening up the actuator itself? Now that I've been fooling around with it, and with the help here, I could probably get everything lined up properly this time...

Frogbone
11-19-2009, 12:21 PM
Add me to the "battery disconnect will kill your actuator" victims.

Disconnected the battery to clear CEL after Seafoam treatment and now I get no air or heat from the dash vents. All I get is windshield and floor air movement.

Tried the fuse 36 trick to reinitialize but no luck with that.

I guess I have to go and get me a new mode actuator, damn it :hissy:

the roadie
11-19-2009, 12:37 PM
Do I just need to buy another actuator and get it put in without ever opening up the actuator itself? When mine died, I was able to open it up, deduce how the calibration software was damaging them, and put it back together repaired. Mine didn't break a gear, but the knurled metal shaft hadn't been pressed deep enough in the white gear, so the shaft spun in relation to the gear. That upset the designed-in relationship of the gear to the blue position feedback sensor (a potentiometer). That's what happens to some of the broken actuators.

If you have a new actuator that doesn't work right out of the box, I can't explain that. For me, when I had the gear and sensor in the right relationship, I could hold the actuator in midair (not attached to the vehicle) and watch it go CW and CCW to detect the endpoints of the motion. Then the control module could put it in the right position to install it to the vehicle. I'd still have to recalibrate it to get its motion IN THE VEHICLE to match what constraints the plenum door put on it, since installed, it will not go as far CW and CCW as it will in free air.

I'm still asking for samples of dead actuators so I can do more engineering analysis. A few people have sent me PMs, and so far, nobody's sent me one. Please consider shipping me your dead actuators as a service to the community. Anybody?

BigJob
11-19-2009, 12:58 PM
So in the event that I have to unhook my battery again, how can I avoid this happening to the new actuator?

Enzymaticracer
11-19-2009, 01:21 PM
When mine died, I was able to open it up, deduce how the calibration software was damaging them, and put it back together repaired. Mine didn't break a gear, but the knurled metal shaft hadn't been pressed deep enough in the white gear, so the shaft spun in relation to the gear. That upset the designed-in relationship of the gear to the blue position feedback sensor (a potentiometer). That's what happens to some of the broken actuators.

If you have a new actuator that doesn't work right out of the box, I can't explain that. For me, when I had the gear and sensor in the right relationship, I could hold the actuator in midair (not attached to the vehicle) and watch it go CW and CCW to detect the endpoints of the motion. Then the control module could put it in the right position to install it to the vehicle. I'd still have to recalibrate it to get its motion IN THE VEHICLE to match what constraints the plenum door put on it, since installed, it will not go as far CW and CCW as it will in free air.

I'm still asking for samples of dead actuators so I can do more engineering analysis. A few people have sent me PMs, and so far, nobody's sent me one. Please consider shipping me your dead actuators as a service to the community. Anybody?

Hi Roadie,

Thanks for the response. I can definitely send you my first actuator, but I dunno how much good it will do you, if after reading my next two paragraphs you would still like it, just PM me to discuss further.

Whats interesting though is that the internals of my new actuator are actually different from the OEM part... it looks like the actuator has been redesigned compared to my first one, I'm assuming to resolve the issue of the final gear from spinning on the arm axis once the arm has hit it's stop.

The new one has two bumps on the top cover, as well as a redesigned gear itself, designed to physically prevent the internal gear from turning any further than its defined range of motion.

If I get around to trying to do some more work on this, I can try to take some pictures and upload them in the interim if people think it will help...

I'm also thinking I may just go ahead and order another part to have around incase I get fed up trying to get my new one working...

Rag PA
04-02-2010, 09:24 PM
I too have experienced the warm air from the driverside vent. This started at the end of the warm weather in Oct 09. I have yet to try the fuse to reset the actuators. But nobody has metioned the additional problems I have. The rear roof vents on the drivers side of my EXT in the 2nd and 3rd rows have no airflow while the passenger side is blowing normally. I haven't found anyone else mention the rear vents. I'll pull the fuse and say a little prayer. I think I was off when I replaced the low pressure switch and spent $40 something for that. I'll repost after I pull the fuse. Just curious about the rear vents since I seen no mention, thanks again ...this will be my 4th time TRAILVOY Saved my pocketbook!:woot:

Rag PA
04-03-2010, 10:35 AM
Pulled the fuse...wasn't sure what I was hearing. Waited 2 minutes and fired it up....rear vents blowing like a hurricane...cant tell if the AC is blowing cold too chilly now to tell but things have changed that's for sure THANX AGAIN GUYS!!!:woohoo:

Warmed up today and the AC worked flawlessly!!!

gmc man
04-03-2010, 01:31 PM
I'M HAVING THE SAME PROBLEMS WITH THE VENTS IN MY 04 ENVOY. THERE IS ENOUGH INFO IN THIS THREAD. WILL USE IT AND LET EVERY ONE KNOW HOW IT WENT:thx

Corey E3
05-22-2010, 01:05 PM
I have read through all the posts regarding the vents and it being caused by mode actuator. I have tried everything and just replaced the mode actuator. Initially air was only coming through the floor/defrost. Now that I had replaced the part it is coming from the front vents. I can feel the gears of both actuators moving when I am switching on the controls but nothing changes. Any suggestions on how to proceed? Is it the control module causing the problem? Thanks in adavnce.

Enzymaticracer
05-30-2010, 10:14 AM
So I finally ordered another actuator from rockauto for like $40 this last weekend. Got it in and now my A/C system is working like its supposed too!

Thanks so much for the instructions!

THE ROOSTER
05-30-2010, 11:22 PM
I had the same problem when I replaced a battery a few years back, and after 2 actuators and it never worked right again... I may have not given the actuator enough time to calabrate itself, so I just unplugged it and used a dime or a quarter and a flash light to manually adjust it from vents to floor... You do not need to remove any part of the dash to get to this actuator...
Now this winter I might replace it one more time and give it time to calabrate...

THANKS

cwalrath
06-01-2010, 03:55 PM
It was $342 total. This repaired the issue of no a/c blowing through the dash vents.

Prior to taking it to the dealership I bought an actuator and attempted to install it without success. It is a a difficult job, in my opinion. The actuator is in an area that is difficult to access that does not give you the ability to see what you are working on so you have to try to install it "blind". At the parts store the actuator was $130, luckily they took it back (they typically will not take this type of part back as a return).

So after two failed attempts and an entire Sunday wasted I took the vehicle to the dealership.

Good Luck!

boaterbill1952
06-28-2010, 04:45 PM
Did the actuators go through their motions and make noises during the recalibration sequence? This is a very important question.

Your mode actuator could have died as a coincidence. The problem is definitely a failure of the mode actuator or the HVAC control box or the wiring between the two.

There are three actuators on the driver's side of the HVAC plenum behind the dashboard covers. The mode actuator is the middle one of the three. If you can disassemble your dash and look at it while it goes through a recalibration process, you can conclude whether or not it's dead. Want to be digging into your dash like that, or just pay a dealer to diagnose it for you? We can talk you through as much of this as you want, or as little.


Hello, I am experiencing the same problem with no ac discharge from center vents after battery disconnect.
I pulled the hvac 2 fuse #36 for a couple minutes. turned ign on after replacing the fuse. HEard some sounds under the dash but same condition.
I can switch from floor to defrost but will not switch to center ducts.
I tank it that the actuator is good just not properly calibrated.
I also understand a dealeer can force calibrate the actuators with a "teck 2".

And, do you leave the hvac switch on when calibrating? You said on prev pose "you will hear the actuators and blower going through it's calibration.

Any help appreciated, Bill

nyc_medic
07-08-2010, 12:35 AM
Hello All,
I have had the same issue. Disconnected my battery and vents stop working. I waited a cople months dealing with the a/c coming from the defrost and floor vents. After driving 3 1/2 in 100 degree heat in bumper to bumper traffic i decide it is time to fix. I didn't have the time or luxury to order the part on line so I paid the stealership price of 82.00.
If you have the right tools it is not that hard to change the part. My 0.02 cents is to go to sears and get a thumb drive that will accept the 5.5mm socket. Made reaching the hard to reach areas easier. Also use tape to secure the screw so i doesn't fall off the socket. I can not take any credit for any of this information but used it and worked like a charm.
Thanks to all who had input.
:thx:thx:thx

DougK
07-08-2010, 03:30 PM
Sooo I am attempting to fix this now myself as well, I can see clearly where I need to be, however unless I am missing something in the removal process I can't get anything in there to the parts out...even to try and open it manually... I have pulled the vent outta the way as per the sticky but no matter what tools or how I try and get in there it's just not working for me... looks like if the steering support was removed I'd be able to get in there without issue...but just the few small things like dash covers just isn't working maybe my hands are just to big....when I was testing the actuator with my hand on you can feel it's spinning inside...so figure for now just manually open it but pfft this 100+ degrees out sure isn't helping either....


I got in there enough to manually turn it, and now I have front vents, now what I noticed was if I set it to the front vent manually then connected it, it would turn and of course turn on the floor, if it's able to turn to put the floor vents on, then the teeth must not be killed inside you would think if it can move them 2-3 teeth or however many, it should be able to reverse itself at the same time....???? My wife is just happy to have a/c blowing on here again, she's due any day, less bitching now :)

mattramirez86
08-07-2010, 09:28 AM
Here you go.

http://forums.trailvoy.com/showthread.php?t=40235

I am trying to take mine out behind the glove box, but can't pull it out because:undecided there is a metal rod that I cannot remove. Any suggestions?

Bubba10
08-20-2010, 11:54 PM
I have tried the recalibarition to no avail. I did find out from dealer the mode actuator they say was shorted out. All I did was remove the old battery and replace a new battery and this shorted out a mode actuator? The AC and ventialtion was working great prior to the battery replacement. Does anyone know of any service bulletins or recalls for this? I have owned a many cars and even completley rebuilt cars from frame out and never heard of just replacing a common battery would short out a ventilation actuator.

Blazernut
08-21-2010, 01:16 AM
I have tried the recalibarition to no avail. I did find out from dealer the mode actuator they say was shorted out. All I did was remove the old battery and replace a new battery and this shorted out a mode actuator? The AC and ventialtion was working great prior to the battery replacement. Does anyone know of any service bulletins or recalls for this? I have owned a many cars and even completley rebuilt cars from frame out and never heard of just replacing a common battery would short out a ventilation actuator.

They don't really short out. They grenade during the recalibration process (plastic gears)

the roadie
08-21-2010, 02:47 PM
...the mode actuator they say was shorted out....Whoever said that was underinformed or lying and you can tell them I said so. :dielaugh: Or else they're disrespecting your intelligence and figure that all the average owner can understand is "there's a short". :rolleyes: :hopeless

One of my pet professional peeves (as an electrical engineer) is people who misuse the specific term "short circuit" when they mean "open circuit".

You need to replace the actuator if multiple system resets didn't fix it.

apcapt
08-26-2010, 01:44 PM
Thanks for the fix, ireplace dmy battery and the wifes TB would not blow out of the front vents. Quick fix thakns again.,

R_PIERCE
03-29-2011, 02:40 PM
Seems like mine just suffered the same fate. Thanks to this thread, tracking down the correct part number was pretty easy. I ordered mine from amazon. $44.42 + Free shipping. Hope this does the trick. I pulled the fuse and that brought no joy.

mattramirez86
03-29-2011, 02:44 PM
What/Where is the dmy battery?

R_PIERCE
03-29-2011, 02:53 PM
What/Where is the dmy battery?

I think OP meant to say "replaced my battery"..

chrsdvs
06-12-2011, 10:21 PM
Has anyone replace a mode actuator in a 2006 Envoy? I have been battling this thing for weeks. I have read the threads for the 2003 models and it sounds much easier. The actuator for the '06 is not behind the duct. All the actuators seem to be behind the instrument panel. Do I need to remove the entire instrument cluster? I have been unable to find anyone addressing the issue for a 2006. PLEASE HELP!!:crazy:

Z06RT
06-15-2011, 07:56 PM
so... here's a question no one asked .. (I think) .. after we get the defective door actuator unit out, and the new one in .... and everything is workin peachy keen ... whats to prevent this from occuring to the new unit in ... oh ... say 6 months when the battery needs to be replaced ... or ... say ... when the ingnition switch module goes bad ... and you need to disconnect the battery to service it .. or service anything electrical for that matter ... is the door actuator going to fry again when we re-connect the battery?????

westtwin
06-15-2011, 08:09 PM
That is one of the reasons I have an adapter to maintain computer memory, you can try turning off all fan, ac and heater controls, disconnect the battery for 15 min and try again, but many times it requires actuator replacement.

Z06RT
06-15-2011, 08:12 PM
I'll bet stealerships do this as well ... you'd think they would send out a notice to owners to use one of these whenever we disconnect the battery!! Just another reason GM is going to hell in a hand basket!

the roadie
06-15-2011, 08:52 PM
I'll bet stealerships do this as well ..Possibly. Never heard a report from a GM tech on the issue, though.. you'd think they would send out a notice to owners to use one of these whenever we disconnect the battery!! Communicate?!? With DIY Owners?!? To save us time, money and frustration?!?!?!

You slay me. ;) :dielaugh:

They HATE DIY owners and thwart us at every possible avenue. That's clear.Just another reason GM is going to hell in a hand basket!One of many. But I bet other platforms have different annoyances.

treborterb
08-22-2011, 10:28 AM
That is one of the reasons I have an adapter to maintain computer memory, you can try turning off all fan, ac and heater controls, disconnect the battery for 15 min and try again, but many times it requires actuator replacement.

Could you tell us more about your adapter that you use to maitain computer memory...pics would be nice:D...Thanks.

Ray Dockrey
08-22-2011, 01:23 PM
I would think most auto parts stores would have them but this is off of Amazon. I have no idea how good it works.

http://www.amazon.com/gp/product/B000J4HHVM/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B002C0NP5I&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1DHM6J5ABAZM82EC6BEJ

hershywirt
09-12-2011, 11:06 AM
or easier: pull HVAC B fuse #36 in the rear fuse block (under the rear seat - driver's side) for 2 minutes. Then put it back in with the ignition off. Then turn the key to the RUN position, but don't start the engine. Don't touch the HVAC controls for 2 minutes, and you should hear the actuators and blower motor going through all the modes and speeds. Then it should be happy and you can drive away.

Thanks Roadie! Had the same issue with my 9-7x. I pulled the fuse & it works like a charm! You da man!

hershywirt
10-18-2011, 06:33 PM
So, I'm having the issue again and the fuse trick isn't solving it. One thing I'm noticing this time is that I feel the air come out the dash vents for maybe a second when the system turns on, but then it stops. Has anyone else noticed this? Thanks!

the roadie
10-18-2011, 06:35 PM
Momentary airflow is a sign that the system is attempting to recalibrate itself. If it fails, and the fuse reset doesn't work, shake your fist in GM's general direction and prepare to swap the actuator.

hershywirt
10-19-2011, 04:31 PM
Momentary airflow is a sign that the system is attempting to recalibrate itself. If it fails, and the fuse reset doesn't work, shake your fist in GM's general direction and prepare to swap the actuator.

I've shaken my fist in their direction a few times already! Thanks again Roadie!

austin1660
11-12-2011, 04:53 PM
Is there a special tool used for pulling out fuses in a 2005 trailblazer?

the roadie
11-13-2011, 02:28 AM
Is there a special tool used for pulling out fuses in a 2005 trailblazer?Tell us what you've tried so far that's failed to work. :confused:

Fingers, needle-nose pliers, Leatherman tool, Swiss Army knife "Champ" model, screwdrivers, all have been known to work. Oh, yeah, and the little plastic doohickey that's in all of the spare fuse collection cases.

Ztryfe
11-17-2011, 10:54 AM
Momentary airflow is a sign that the system is attempting to recalibrate itself. If it fails, and the fuse reset doesn't work, shake your fist in GM's general direction and prepare to swap the actuator.


:cry:

Looks like my actuator is borked! Upon recalibration I get exactly that.

Time to dive under the dash!

Thanks for the info roadie

mandingo98
06-24-2012, 11:13 AM
I had this problem and thanks to this site, I was able to narrow it down to my mode acutator not working. I fixed it without any new parts. I have an 2006 trailblazer with manual controls. I pulled the lower dash and black panel below off. Just a couple of bolts 7mm I think, two below the steering wheel have plastic covers. You need to pull that rectangular long curvy foot vent on the driver side under the dash out they way. It's held in by one plastic pin on the door side that just pops out and in, so pull it down from the door side and don't be afraid. Then when laying down under there you can see 3 black acutators. The one by the firewall is for the window defroster and floor vents. The one next to that is for the main vents. Not sure what the one close to the steering wheel is for. Pull the HVAC fuse under the rear passenger seat out for 30 secs. and put in back in. Put the key in the ignition, but DON'T TURN IT YET. Lay back down and then turn the key. You will see the silver slotted gears on the actuators reset. My main vent was not moving, problem found. I took it out, with some patience and a 7/32 socket on a small screw driver, it also has a connecter the you just press and pull out. Don't drop the screws. It has a white gear attached to it that can be pulled out. Remember the postions. Then after going to buy one, I got the wrong one and had to return it. The only store around with it in stock was NAPA and they were also the only ones that closed at 5:00. So I thought I would have to wait a day, and then decided to look inside the actuator. While closed I could not turn the gear. I opened it and saw all the gears and the motor. I pulled the motor out and the gears could all turn, bad motor right, wrong. I put the motor back in and pressed all the gears. the small green one attached to the mother board went down and was not connecting with the big gear. I raised it a little and decided to give it a try. Hooked it up with out putting it back in, did the reset again and it moved but then stopped. I disconnected it and opened it again. That same gear was down again. This time I put it up as high as it could go, put the cover on gently and flipped it upside down, then snapped it in place, so I wouldn't vibrate the gear down. I put the white gear back in and had to hook it up and let it run a little, then stop because it was all the was to one side and wouldn't line up, screwed it in and was back in business. Everything worked. This may not work for everyone, some have said their gears were broken inside. Mine were fine, just the one with the motherboard slipped.

murfgjr
10-01-2013, 03:06 PM
I'm having sort of the same problem with an 04 I just bought. The difference is it won't blow out of the floor vent and seems to leak some when some in the defroster when in upper vents, ie. frosting the windshield. I have tried the fuse removal and hear some noise when I have returned the fuse and try the switch, but still no luck. Any HELP! Roadie???

Roamingdoc
10-01-2013, 05:02 PM
Hmmm, well, I am not the authority but often that is a sign of heater core issues (has been for me that is)... but others will chime in and I'm sure give you some good advice. Great forum with lots of help.

murfgjr
10-05-2013, 09:46 AM
I'm having sort of the same problem with an 04 I just bought. The difference is it won't blow out of the floor vent and seems to leak some when some in the defroster when in upper vents, ie. frosting the windshield. I have tried the fuse removal and hear some noise when I have returned the fuse and try the switch, but still no luck. Any HELP! Roadie???