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HVAC Mode Actuator door replacement

862K views 737 replies 338 participants last post by  Ravalli Surfer 
#1 · (Edited by Moderator)
I just replaced my mode actuator due to the dash vents not working; it wasn't too bad of a job; you just need to be patient and smart as you work.

First you need to find out what part number to order; just call the local GM dealer. you will need to give them your VIN; the P/N I used was 89018675 and I got it from parts4chevys. $46.33 which was a lot cheaper than the dealership.

Remove lower dash covers. The actuator is located behind the middle portion of the dash; if you lay on the floor and look to the left you will see it.

Remove gray air duct as shown in pc #53; just pull it from its endpoint; this way you can get to the actuator better.

There's 2 actuators; you want the one with the white gear coming out the side; it's the lower one in pic #52. You will need a 5.5mm socket to get the 2 screws out; be careful not to drop the screws; take your time.

Pic #46 shows the actuator; the two horizontal holes are where the screws mount; the other one close to the wire connection has a dowel that helps locate the actuator. You will need to adjust the white gear shown in pic #46
to be at the same location as the gear on the actuator you removed in order for it to go back in correctly. There are 3 marks on the back of the plastic housing (as seen in pic #46) and also slots in the metal part of the gear drive, the top slot is in the 1'oclock position in pic #46. Be sure your new actuator gear position matches the old and it will drop right in. I put the screws in the socket and then wrapped electrical tape around them so the screw wouldn't fall out during assembly. The whole thing took me 45 minutes.
The vents now work like a charm and I saved a bunch of coin!

You can doooo eeeet!
 

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#715 ·
MAY03LT,
I really enjoyed all of the YouTube videos and how to's through the years..very educational, and even in the most confusing times for me, sometimes you kept me laughing..I want to thank you for the knowledge you gifted me and the help to keep me patient..You're truly amazing, THANK YOU..!!
 
#13 · (Edited by Moderator)
All the work is done from the drivers side.

03Huggy, what prompted you to replace the Actuator? Currently my wifes '02 Envoy makes a clicking sound when you changes modes, like from the upper vents to the lower vents, etc. The air still comes out, but it makes the clicking noise like it is binding as it is changing positions. I didn't know if this is what you were experiencing or not?
Thanks
Read my initial post again; it was due to the dash vents not working. The actuator door allows air to go to the dash vents and floor vents.
 
#27 ·
The problem with mine is the dash and defroster vents work, but I have no floor vents.
I have the same problem.....I also cannot turn the defroster vents off if I want.

I did replace the mode door actuator and it clicks less but still does not work correctly.

I think the actuator works but the door itself cannot move the whole range for some reason.
 
#9 ·
03Huggy, what prompted you to replace the Actuator? Currently my wifes '02 Envoy makes a clicking sound when you changes modes, like from the upper vents to the lower vents, etc. The air still comes out, but it makes the clicking noise like it is binding as it is changing positions. I didn't know if this is what you were experiencing or not?
Thanks
 
#14 ·
#16 ·
2002 TB HVAC Mode Door Actuator Replacement

I'm new posting here but have found this forum extremely helpful in researching both my 2002 trailblazer and a 2004 Envoy. Thanks to everyone who participates here.

I have researched this problem on the 2002 TB here, purchased the part and started taking things apart today to check out the real estate available for the repair. The only major obstacle I see is clearance to remove the lower screw holding the actuator in place. There is a metal brace supporting the steering column and there isn't enough space between the brace and the actuator to get the ratchet and socket into position. Has anyone experienced this problem in replacing these, and if so, how did you get around it without removing the brace?

Thanks again for a great forum!
 
#17 ·
The only major obstacle I see is clearance to remove the lower screw holding the actuator in place. There is a metal brace supporting the steering column and there isn't enough space between the brace and the actuator to get the ratchet and socket into position. Has anyone experienced this problem in replacing these, and if so, how did you get around it without removing the brace?

Thanks again for a great forum!


I had a "shorty" 1/4" nut driver. Put the socket on the end of it and it went up there no problem. Also had a 1/4" short ratchet that helped too. Don't forget when replacing the screws. Wrap some tape on the screw and socket. Works every time....

Also fill out your ID page so we know what you drive
 
#18 ·
I've changed the accuator once already on my "02 TB and gotta say the next day the "ticking" or "clicking" sound came right back very soft & low like... now 3 weeks later it "ticks" or "clicks" faster and louder. I'm kind'a hopnig someone might be helpfully with another though on fixing it or possible thinking it might be something else.... any help?
 
#19 ·
REmoving Panel at bottom of steering column

Is there any trick to removing the panel underneath the steering column to access the actuator. I removed all the screws, but the panel would not come out. Are there any "ears" that interlock with the trim pieces on either side of it?

I didn't want to pry on anything until I understood better how to remove it.

TIA for the help.
 
#20 ·
hi, great forum, thanks for all the great info. i hope this thread is the answer to my problem and i hope others can give me ideas.

2003 sle envoy. i recently (well last few months ) am only able to have A/C or heat come out of the front vents on the 3rd setting on the nob. A/C and heat works but only blows out strong on 4th and 5th setting and NOW today only on the 5th setting. before i had the battery die and had throttle problems and was able to fix it with a good cleaning of it...thanks to the forum. do you think its the " mode door actuator " that needs to be replaced? i too have had the clicking sound but strange as it might be only time i hear it is during the winter months. thanks for any help and great forum with great info.
 
#21 ·
hi, great forum, thanks for all the great info. i hope this thread is the answer to my problem and i hope others can give me ideas.

2003 sle envoy. i recently (well last few months ) am only able to have A/C or heat come out of the front vents on the 3rd setting on the nob. A/C and heat works but only blows out strong on 4th and 5th setting and NOW today only on the 5th setting. before i had the battery die and had throttle problems and was able to fix it with a good cleaning of it...thanks to the forum. do you think its the " mode door actuator " that needs to be replaced? i too have had the clicking sound but strange as it might be only time i hear it is during the winter months. thanks for any help and great forum with great info.
Hi, welcome to the site.
The mode doors only control the direction of the air flow (floor/vent/dash), have nothing to do with the fan speed.
It sounds like you are having a problem with the fan speed control module. I think it's called a blower motor resistor assembly. Very common problem, it's a $25.00 fix (if u do it yourself) and located under the dash, behind the glove box. Lots of info on here, and some pictures. Try a quick search, the more recent threads are the ones to view.
You may also have a mode door problem, but the speed thing is the resistor assembly.
 
#22 ·
thanks for your reply. after posting i did some more reading and there was someone who also had or has the same problem. the vent would or seem to not have any air/heat/ac coming threw when i turned the nob on. setting 1,2,3, now 4 acts like the off position and 5 is the only setting that pushes anything out. i'm hoping that the person who also had the same problem post a reply. do you know of any good places in Canada to buy parts besides places like CrappieTire? i also need to replace the spare tire carrier. seems like this truck needs some upkeep.

thanks
 
#25 ·
Hot & cold at the same time

I've been searching high and low, and I'm hoping the pictures here will help. I get air through the various vents, but on the drivers side it's only warm air while the A/C works fine on the passenger side.
By looking at the directions and pictures, can I assume that the upper actuator is the one that I will need to replace to get cold air out of the driver's side vents?
The pictures do help, if it wasn't for them I wouldn't know what to look for. My Chilton's manual is useless in providing any help on this subject.
 
#26 ·
I've been searching high and low, and I'm hoping the pictures here will help. I get air through the various vents, but on the drivers side it's only warm air while the A/C works fine on the passenger side.
By looking at the directions and pictures, can I assume that the upper actuator is the one that I will need to replace to get cold air out of the driver's side vents?
The pictures do help, if it wasn't for them I wouldn't know what to look for. My Chilton's manual is useless in providing any help on this subject.
Same here, drivers side blazing hot, passenger and rear nice and cold. This also happened the same day the battery had to be replaced. Has anyone had this problem and fixed it?
 
#31 ·
Great Write Up! Thank You, now I know what that sound is! I'm wondering if there could be something binding it elsewhere in the system, or is it that the plastic wheel just get brittle over time and looses teeth? For those that have replaced this part, what do you think?
 
#32 ·
We took min apart to see what the issue is and they use gears with very fine teeth. On mine a couple of the teeth were missing. The other thing you can do is if you don't use the floor vents then just unplug the actuator and manually move it until the air is coming out the vents and then just leave it unplugged. This is what I will do next time as I never use the floor vents anyway.
 
#66 ·
03Huggy....Thank you so very much for the pictures and information :yes::tiphat its just awesome .. the thing is tho mine didnt/not clicking at all :confused: its not working but i tried to listen to it and even laid down looking at it, didnt even move :undecided

The other thing you can do is if you don't use the floor vents then just unplug the actuator and manually move it until the air is coming out the vents and then just leave it unplugged. This is what I will do next time as I never use the floor vents anyway.
thats me !i dont care about the floor vents! but wont manually brake the remains of it ? :undecided
 
#33 ·
Hello,

Great read.I know I am in the Trail Blazer forum, but I'm having same issue with my 2002 tahoe, do you know if this procedure will work with my tahoe? If not do you have any suggestions for me?

Thanks to all


I just replaced my mode actuator due to the dash vents not working; it wasn't too bad of a job; you just need to be patient and smart as you work.

First you need to find out what part number to order; just call the local GM dealer. you will need to give them your VIN; the P/N I used was 89018675 and I got it from www.parts4chevys.com for $46.33 which was alot cheaper than the dealership.

Remove lower dash covers. The actuator is located behind the middle portion of the dash; if you lay on the floor and look to the left you will see it.

Remove gray air duct as shown in pc #53; just pull it from it's endpoint; this way you can get to the actuator better.

There's 2 actuators; you want the one with the white gear coming out the side; it's the lower one in pic #52. You will need a 5.5mm socket to get the 2 screws out; be careful not to drop the screws; take your time.

Pic #46 shows the actuator; the two horizontal holes are where the screws mount; the other one close to the wire connection has a dowel that helps locate the actuator. You will need to adjust the white gear shown in pic #46
to be at the same location as the gear on the actuator you removed in order for it to go back in correctly. There are 3 marks on the back of the plastic housing (as seen in pic #46) and also slots in the metal part of the gear drive, the top slot is in the 1'oclock position in pic #46. Be sure your new actuator gear position matches the old and it will drop right in. I put the screws in the socket and then wrapped electrical tape around them so the screw wouldn't fall out during assembly. The whole thing took me 45 minutes.
The vents now work like a charm and I saved a bunch of coin!

You can doooo eeeet!
 
#35 ·
uh curious...

Now i'm guessing maybe actuator causing this...No matter which mode i put my 2002 ENVOY SLT in (floor, defrost, defroster/ floor...) I ALWAYS get air coming out the dash vents. The Dash vents do NOT want to close unless i manually close the vent shade things. Do i need to replace this actuator or should i just replace the climate control assembly? Thank you.:confused:
 
#36 ·
Now i'm guessing maybe actuator causing this...No matter which mode i put my 2002 ENVOY SLT in (floor, defrost, defroster/ floor...) I ALWAYS get air coming out the dash vents. The Dash vents do NOT want to close unless i manually close the vent shade things. Do i need to replace this actuator or should i just replace the climate control assembly? Thank you.:confused:

Nycjinbx,

Im having the same issue with my 02 tahoe. I thought it was the climate control assembly as well, so I replaced it for about $100 bucks. It didnt work for me. Im thinking its the actuator. Im having a hard time locating it on my truck. Im going to the dealer tomarrow to get the part & should have it installed by end of the week. ill let you know my results
 
#39 ·
It is the mode door actuator. Do a search and you will find a how-to plus you will see the threads that I have started on this. The mode door actuator on the 2002 is tricky because the shaft is pressed onto the actuator itself and according to GM requires a special tool. We were able to do it without the special tool and I explain how in that thread.

Here you go. I found it for you.

http://forums.trailvoy.com/showthread.php?t=45175&highlight=actuator
 
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