Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

Front vents not blowing??

153K views 107 replies 49 participants last post by  bgbevan 
#1 ·
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?
 
#64 ·
Just had an actuator replaced at the dealership

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!
 
#66 ·
Fixed front vents not blowing

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
 
#67 · (Edited)
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 :)
 
#69 ·
2006 TRailblazer LT Mode Actuator

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.
 
#70 ·
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)
 
#73 ·
Changed battery now top vents don't blow air.

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.
 
#76 ·
Mode actuator

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:
 
#77 ·
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?????
 
#80 ·
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.
 
#90 ·
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.
 
#91 ·
04 Trailblazer

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???
 
#93 ·
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???
 
#98 ·
My 2002 Trailblazer was only blowing out the Dash vent after replacing the battery this last spring, Then when my wife tried the AC, the pop off valve kicked and lost some refrigerant, I let it be since I usually don't use the AC anyway, Now it is cold and the floor vents are not working. I tried the reset with no luck. I took out the center actuator and and tore it apart, Low and behold a broken gear, I replaced the actuator and now when I put it on dash vents it blows out on the floor and when I put it on floor vents it blows out on the dash, Almost like it motor in the actuator is turning the wrong way. The actuator came from a 2002 Envoy (Inspected and the gears all look good.) I tried the reset procedure again and it did not change a thing. Any advice would be appreciated. This has the digital climate control system in it, I Tried a different one and have the same result.
 
#99 ·
A/C vents inop.

I have read/viewed many posts regarding this common problem of air flow not coming from vents after battery replacement. I also have same problem, but now I can verify problem as inoperative Mode Actuator. Videos and posts were very helpful and I have ordered actuator from Amazon. I have seen a post asking how to avoid this problem again. Is there an easy way such as leaving control head in a certain position before disconnecting battery or disconnecting fuse with Ignition Switch in run mode? I would like to thank ALL who helped with this common problem, maybe Chevy is paying attention.
 
#101 ·
I just signed up to say thank you for all the help in this and other associated threads.

02' trailblazer LTZ would not blow out the dash vents. live in SoCAl so AC is a must. This forum saved us from replacing a paid for car.

In my case, I removed the blend door actuator and found the gears had stripped out, bought a universal replacement from auto-zone for way too much money but it worked and I don't have time to ****er with this for weeks on end.


Found the defroster actuator was slipping. Not as bad and defroster isn't a must have in SoCal. I mended it with JB wield. I have low expectations for it's longevity but I will report back with the outcome.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top