hvac actuators and dash removal

dcbenvoy

Original poster
Member
Jan 28, 2012
51
Well it looks like mt passenger temp door acuator is going. I already replaced the dash / floor one but it needs mor adjustment.

I removed my dash from my dodge truck once and found it to be easyier than I expected. I know you don't have to do it but would it make it alot easier to do the repairs.

Any good resources with that info in it.
 

Me007gold

Member
Nov 20, 2011
1,106
Its going to take a few hours to remove the dash or so Ive heard. I think it would take a whole lot less time that that to change the actuator with out taking out the entire assembly.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
That actuator is changeable if you cut part of the metal bracket out of the way. I took the entire dash out once in a couple of hours for another project, and the actuator was still trapped by the bracketry.

dash04.jpg


allactuators-orig.jpg
 
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dcbenvoy

Original poster
Member
Jan 28, 2012
51
Ok now I may seem crazy but one you get that far can't you just remove the whole unit so you don't have to cut the bar.

I am thinking about taking it out and replacing all the actuators at once.
 

The_Roadie

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Nov 19, 2011
9,957
Portland, OR
The heater core and AC heat exchanger are inside the plenum unit, so removing it involves plumbing and evacuation of the AC refrigerant. Easier to cut metal bracing than that.

As the old joke goes, on the car assembly line, they put the heater core on a little pedestal. Then the entire vehicle gets assembled around that seed.
 

dcbenvoy

Original poster
Member
Jan 28, 2012
51
That reminds me why I took it out the whole thing in my truck. Because it needed the core replaced. My bad.

So how do you get to that area? Through the glove box? What did you cut out the metal with?
 

The_Roadie

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Member
Nov 19, 2011
9,957
Portland, OR
dcbenvoy said:
So how do you get to that area?
Take off the dash trim panels.
What did you cut out the metal with?
Dremel with cut-off wheel. Die grinder with burr bit. Drill lots of little holes and twist off the parts left behind. Lots of ways. Be creative. Depends on what tools you have in stock and what you're willing to buy to add to your kit. :wootwoot:
 

dcbenvoy

Original poster
Member
Jan 28, 2012
51
Ok cool.

No new tools here, I already have that stuff I was just checking.

This is the nicest project car I have ever owned. A project I'm not so sure I wanted.:smile:
 

am-radio

Member
Apr 24, 2012
178
Hi Everyone,
I'm new here. I just bought a 2006 Envoy Denali. I am now having the classic no air flow through my dash vents. I have it on the floor and defrost. I can't hear the motor click and not sure if it even moves. I tried resetting the fuse, but that didn't work. I'm guessing it's the airflow mode actuator. How much of my dash do I have to rip apart to get to it? Will the height adjustable pedals be in the way? I read that on the Denali I will have to remove the bolts on the gas pedal and let it hang to the side. The moulding under the steering wheel and dash will have to me removed and part of the side dash I believe. Also part of the airflow ducting has to be removed I believe, from what I've read. I have also read that I should have the heater control settings blowing to a certain position as the new part comes shipped at a certain position. What if the part is set to dash vents but the flapper door is set to floor? Will the part get wrecked again? Is there a certain way to install? Will I have to do another fuse reset once installed? Are GM parts better than aftermarket on this actuator. I live in Canada and shipping is usually not worth it, so after shipping, taxes and brokerage fees, it's usually cheaper to buy from the dealership. Thanks.
 

Me007gold

Member
Nov 20, 2011
1,106
am-radio said:
Hi Everyone,
I'm new here. I just bought a 2006 Envoy Denali. I am now having the classic no air flow through my dash vents. I have it on the floor and defrost. I can't hear the motor click and not sure if it even moves. I tried resetting the fuse, but that didn't work. I'm guessing it's the airflow mode actuator. How much of my dash do I have to rip apart to get to it? Will the height adjustable pedals be in the way? I read that on the Denali I will have to remove the bolts on the gas pedal and let it hang to the side. The moulding under the steering wheel and dash will have to me removed and part of the side dash I believe. Also part of the airflow ducting has to be removed I believe, from what I've read. I have also read that I should have the heater control settings blowing to a certain position as the new part comes shipped at a certain position. What if the part is set to dash vents but the flapper door is set to floor? Will the part get wrecked again? Is there a certain way to install? Will I have to do another fuse reset once installed? Are GM parts better than aftermarket on this actuator. I live in Canada and shipping is usually not worth it, so after shipping, taxes and brokerage fees, it's usually cheaper to buy from the dealership. Thanks.

The Mode actuator is 'easy' to get to, There is a trim panel under the dash(that has the obdii port on) that has to be removed, as well as the vent tube thats under the dash. Thats all that you really have to remove.
 

AbsoluteZero

Member
Nov 21, 2011
211
am-radio said:
Hi Everyone,
I'm new here. I just bought a 2006 Envoy Denali. I am now having the classic no air flow through my dash vents. I have it on the floor and defrost. I can't hear the motor click and not sure if it even moves. I tried resetting the fuse, but that didn't work. I'm guessing it's the airflow mode actuator. How much of my dash do I have to rip apart to get to it? Will the height adjustable pedals be in the way? I read that on the Denali I will have to remove the bolts on the gas pedal and let it hang to the side. The moulding under the steering wheel and dash will have to me removed and part of the side dash I believe. Also part of the airflow ducting has to be removed I believe, from what I've read. I have also read that I should have the heater control settings blowing to a certain position as the new part comes shipped at a certain position. What if the part is set to dash vents but the flapper door is set to floor? Will the part get wrecked again? Is there a certain way to install? Will I have to do another fuse reset once installed? Are GM parts better than aftermarket on this actuator. I live in Canada and shipping is usually not worth it, so after shipping, taxes and brokerage fees, it's usually cheaper to buy from the dealership. Thanks.

Airflow only from lower level is typically related to the actuator shown in Roadie's post as "Floor/Dash Vent Mode" on the left (driver's side) of the unit. It can be changed without removing the dash. Last winter I changed the Defrost actuator servo just above it. You have to be somewhat of a contortionists but I don't have any lingering bad memories. I don't have adjustable pedals so can't comment. Also I don't know if there's any issues because you have the V8. Can't imagine there is but I don't know. I bought my servo thru Amazon but can't comment on shipping/cost issues to Canada. I'd suggest you remove the lower hush panel and have a look. You can see the servos in question and judge if they're accessable.
 

am-radio

Member
Apr 24, 2012
178
Thanks. I am going to try to remove the panels and have a look next week, once I make some room in my garage.
 

jemmie

Member
Jan 7, 2012
49
I have a 2005 GMC Envoy SLT XL 4.2L 4x4 and today, as it hit 93F, only warm air came out of driver side. I have done some research here and the old site and have tried removing fuse 36, disconnecting battery, etc. and nothing seems to fix it. Air comes from all the vents (top, front, bottom, etc.) but the driver side is warm.

So I'm guessing it's the driver side heater door actuator? Anyone have a different diagnosis?

I am going thru the instructions available on the various sites and it seems like a PITA. I have Dremel and almost all the various tools and have upgraded the stereo system myself so I have messed around with the center console. But there doesn't seem to be a good step-by-step instruction for replacing this. Can anyone help?

Thanks.
 

AbsoluteZero

Member
Nov 21, 2011
211
jemmie said:
I have a 2005 GMC Envoy SLT XL 4.2L 4x4 and today, as it hit 93F, only warm air came out of driver side. I have done some research here and the old site and have tried removing fuse 36, disconnecting battery, etc. and nothing seems to fix it. Air comes from all the vents (top, front, bottom, etc.) but the driver side is warm.

So I'm guessing it's the driver side heater door actuator? Anyone have a different diagnosis?

I am going thru the instructions available on the various sites and it seems like a PITA. I have Dremel and almost all the various tools and have upgraded the stereo system myself so I have messed around with the center console. But there doesn't seem to be a good step-by-step instruction for replacing this. Can anyone help?

Thanks.

Some times if the system is low on refrigerant the temperature can be non-uniform across the evaporator. This can cause a side-to-side difference in temperature. You might verify the system hasn't leaked and is properly charged. Not saying your diagnosis isn't right, just something else to check.
 

jemmie

Member
Jan 7, 2012
49
AbsoluteZero said:
Some times if the system is low on refrigerant the temperature can be non-uniform across the evaporator. This can cause a side-to-side difference in temperature. You might verify the system hasn't leaked and is properly charged. Not saying your diagnosis isn't right, just something else to check.

Interesting you posted that. You are exactly right. I just came back in from diagnosing it some more...

It's leaking freon. I added some freon, it blew cold air, and then within seconds it blew warmer air. I added a second can and the same thing happened.

Unless the Envoy A/C system is very easy to work on, I'm going to take it in this week. Someone please let me know. Thanks!
 

am-radio

Member
Apr 24, 2012
178
I'm at a stand still. My air flow actuator is NFG. I have no air flow coming out of my dash. I ripped everything apart, got the old actuator out. Comparing it to the new one, the external white teeth that mesh with the door are at different spots. The old one was at about 3 o'clock. This seems to be close with the flapper. The new one has the external white piece about 1:30 to 2:00. I can move the flapper by hand, so I can line it up. But as soon as I let go of the flapper, it falls to closed. How do I get the flapper to stay more open so I can mesh it with the new air flow actuator?
 

am-radio

Member
Apr 24, 2012
178
I just took the old actuator apart and it turns freely and moves the white external driver. I thought something was suppose to strip with these? Or is it the motor that fails? I'm hoping I'm not doing this work for nothing. I didn't visually check to see if the flapper was moving before tearing it apart as I couldn't really fit under the dash. Picture of actuators. Left is old, right is new one.View attachment 21117
 

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The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Sometimes a gear tooth breaks in the gear train, and other times the metal hub isn't tightly pressed into the final gear center. When the actuator goes through its recalibration process, the control module slams it from end to end to discover where the flap door hits its mechanical stops and the gear train stalls. If the powerful reduction gear train ends up spinning the final plastic gear on its metal hub, then the relationship between the final gear and the small blue gear (the position feedback potentiometer) will be changed. THIS is difficult to regain.
 

am-radio

Member
Apr 24, 2012
178
Thanks Roadie. Is there a way to get the flapper to sit up so I can get it to line up with the new actuator external teeth?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
To stick the flap in place I'd apply some silicone grease at the shaft then freeze-spray it to turn it gummy. Or spin the motor gear and get the actuator to line up with its current position. The next recalibration will make it all work. I personally pre-aligned the actuator to the shaft.
 

am-radio

Member
Apr 24, 2012
178
I thought if you spun then motor gear and changed the external driver position, you'll have issues. I thought where it comes set when you buy a new actuator is the best spot for it, so when it does do its calibration it has a range to travel each way.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
It's crazy enough that the calibration process overtorques the hub/gear press-fit area. It would be positively insane for the coders to write an algorithm that demands the actuator be in the mid-range position to run properly. Especially since the actuators can be in any position when owners run down or disconnect their batteries and force a recalibration. I wouldn't worry about prepositioning the gear.
 

BRomanJr

Member
Dec 9, 2011
371
am-radio said:
Thanks Roadie. Is there a way to get the flapper to sit up so I can get it to line up with the new actuator external teeth?

When I did mine, I partially engaged the two gears' teeth (there is a larger tooth on one and matching larger slot on the other) and then rotated the actuator into place while still engaged with the flap, this should swing the flap and stay engaged while you position the actuator and get the screws in.

IIRC, The access was tight and I didn't get it lined up and bolted in the first time, patience should prevail.
 

am-radio

Member
Apr 24, 2012
178
the roadie said:
It's crazy enough that the calibration process overtorques the hub/gear press-fit area. It would be positively insane for the coders to write an algorithm that demands the actuator be in the mid-range position to run properly. Especially since the actuators can be in any position when owners run down or disconnect their batteries and force a recalibration. I wouldn't worry about prepositioning the gear.

Roadie, should I just take the cover off my new actuator, pull out a pulley, turn the external flapper driver to match the ducting flapper, reinstall the pulley, put the cover back on the actuator, install the actuator and enjoy cold dash air flow again?
 

am-radio

Member
Apr 24, 2012
178
Well, I got the actuator finally installed. I had to take it apart and move the external white flapper driver to line up with the flapper. Installed (after much swearing, scratches and making my body move in positions it hasn't in year), put everything back together and it works. Thanks everyone for your help.

What I did on a 2006 Envoy Denali
Put the seat right back
I didn't lift the pedals (but I should of) There would of been more room for my fat head
Shut off HVAC system
Disconnect battery
Took all the trim off from the steering wheel down
I took the gas pedal off and let it hang to the side
I took the floor heat ducting off (there is one sensor in the ducting that has to be discontected)
Unhooked power to old actuator
Took out actuator (2 screws, I used a 7/32 socket) Mine were not very tight. I managed to get a very small ratchet up in there.
Fought forever to get the new one lined up
To install the screws without losing them, I put them in the socket and taped them on. Once the screw was started, just pull the socket and take the tape off. This saves tons of time trying to find the screw that keeps falling out of the socket.
Installed power to actuator
Put everything back together
Connect battery
Turn key on and let HVAC do its calibration
Start truck, turn on HVAC and enjoy the air out of the dash and smile knowing you saved a thousand dollars by not taking it to the dealership.
 

91RS

Member
Dec 4, 2011
105
Just to note, the HVAC case is NOT easy to remove in these. It is attached to the dash carrier, NOT the firewall like in the full-size trucks. You will have to evacuate the A/C system to remove it.

89.jpg


92.jpg


93.jpg
 

ksimm92

Member
Apr 28, 2012
166
I just received my actuator in the mail today, so I will be replacing it this evening. One thing I was wondering was obviously the factory one is known to get out of sync or fail after a battery disconnect or drain. Could the new AC delco one I am replacing it with do the same thing?

If so, is there anything I could do to prevent this from happening again if I need to disconnect the battery from some reason? (if the battery drains obviously nothing i can do about that)

Thanks in advance for and input! :smile:


EDIT: I replaced the actuator, here is what i noticed.

I read earlier that someone was having difficulty lining up the gears, i noticed that if you angle the actuator with the white plastic part first and get the gears touching, then while keeping the gears touching you can maneuver the actuator body onto place. Essentially moving the flap gears with the new actuator. (if that makes sense)

I removed the bottom panel that has the OBDII port, and then pulled off the lower air duct, I had PLENTY of room to get at the actuator then.

I was expecting this to be a HUGE pain the in ass, but it took me all of 15-20 minutes.

one thing worth mentioning, my actuator went out about a year ago and i am just now getting around to replacing it. Obviously during the winter you want air on both feet and higher up, and the summer pretty much only higher up. what i ended up doing was unplugging the mode actuator but leaving it in place, then i used either a nickle or quarter (i forget now) and stuck that into the notches on the outer side of the actuator and manually spun it to the setting i wanted.
 

BRomanJr

Member
Dec 9, 2011
371
ksimm92 said:
I just received my actuator in the mail today, so I will be replacing it this evening. One thing I was wondering was obviously the factory one is known to get out of sync or fail after a battery disconnect or drain. Could the new AC delco one I am replacing it with do the same thing?

If so, is there anything I could do to prevent this from happening again if I need to disconnect the battery from some reason? (if the battery drains obviously nothing i can do about that)

Thanks in advance for and input! :smile:

The actuators don't go "out of sync", the controller forgets where the endpoints are and attempts a re-sync to find them again. This re-sync can fail if an actuator is damaged or defective in some way.
The physical damage that occurs during the re-sync happens when the actuator is commanded to go full travel both ways. Where it stops at both ends is recorded in the controller.

We might assume the new actuator is manufactured to the same or higher quality standards given the large number of failures. But certainly could fail in the same manner, but only after years (hopefully) of service.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
ksimm92 said:
If so, is there anything I could do to prevent this from happening again ...
Only if you go back in time and kill the grandparents of all the idiot GM designers who worked on the recalibration algorithms in the HVAC controller. It may only be ONE guy who screwed up the coding. I don't know, or else I'd fly there and slap him myself.

Some number of actuators are just weak, and roll over and die when recalibrated after they age. They must have passed the INITIAL recalibration or else they would not have left the factory or survived the warranty period. I think it's impossible to predict lifetime, just as it's impossible to get GM to FIX the algorithm that kills some small number of actuators when owners of aging trucks discharge or change their batteries.

Edit: BRomanJr is right, of course. My post is funnier, though. :raspberry:
 
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ksimm92

Member
Apr 28, 2012
166
BRomanJr said:
We might assume the new actuator is manufactured to the same or higher quality standards given the large number of failures. But certainly could fail in the same manner, but only after years (hopefully) of service.

thanks, I hope it does last years!
 

ostrouchov

Member
Jun 28, 2012
2
the roadie said:
Only if you go back in time and kill the grandparents of all the idiot GM designers who worked on the recalibration algorithms in the HVAC controller. It may only be ONE guy who screwed up the coding. I don't know, or else I'd fly there and slap him myself.

Some number of actuators are just weak, and roll over and die when recalibrated after they age. They must have passed the INITIAL recalibration or else they would not have left the factory or survived the warranty period. I think it's impossible to predict lifetime, just as it's impossible to get GM to FIX the algorithm that kills some small number of actuators when owners of aging trucks discharge or change their batteries.

Edit: BRomanJr is right, of course. My post is funnier, though. :raspberry:

Roadie, I am new here from Trailvoy and searching for what may be a HVAC Blend Door Actuator problem. Newly installed AC compressor, cools excellent on passenger side but not so much on Driver side. Prior to old compressor failure the temperature out of the pass and driver vents was equal. I cannot find anyone replacing the blend door actuator so I wonder how easy it is and where exactly is the actuator. I am just going to start to troubleshoot it this weekend.

Another question, can the actuator be repaired mechanically so it can re-calibrate itself or is the calibration failure irrepairable without accessing the program/code? I like to go into the "nitty gritty" sometimes instead of buying complete replacement parts, or at least give it a try before I buy. Thanks.:smile: 2005 Envoy XL SLT, 4.2L
 

BRomanJr

Member
Dec 9, 2011
371
ostrouchov said:
Roadie, I am new here from Trailvoy and searching for what may be a HVAC Blend Door Actuator problem. Newly installed AC compressor, cools excellent on passenger side but not so much on Driver side. Prior to old compressor failure the temperature out of the pass and driver vents was equal. I cannot find anyone replacing the blend door actuator so I wonder how easy it is and where exactly is the actuator. I am just going to start to troubleshoot it this weekend.

Another question, can the actuator be repaired mechanically so it can re-calibrate itself or is the calibration failure irrepairable without accessing the program/code? I like to go into the "nitty gritty" sometimes instead of buying complete replacement parts, or at least give it a try before I buy. Thanks.:smile: 2005 Envoy XL SLT, 4.2L

The actuator failure is usually the cracking of a plastic gear that allows the gear hub to slip inside the gear and loses sync. This can be glued, but reliability is in question and the synchronization of the output gear and feedback potentiometer must be correct.

When temperatures are warmer on drivers side, I will lower the fan speed, if the temp gets colder, it is usually low on freon, check with gauges.

If you are sure it full of freon, check driver temp actuator and door movements.
 

ostrouchov

Member
Jun 28, 2012
2
BRomanJr said:
The actuator failure is usually the cracking of a plastic gear that allows the gear hub to slip inside the gear and loses sync. This can be glued, but reliability is in question and the synchronization of the output gear and feedback potentiometer must be correct.

When temperatures are warmer on drivers side, I will lower the fan speed, if the temp gets colder, it is usually low on freon, check with gauges.

If you are sure it full of freon, check driver temp actuator and door movements.

Thanks BRomanJr, I will start troubleshooting this weekend. First the easy stuff with fuses etc. and then examine how tight it will be to remove the actuator if freon is ok. The temps in Toronto this weekend are supposed to be in the high 80's or low 90's ! :yes:
 

sflhomes

Member
Apr 4, 2013
1
I can't seem to get the old accuator to come out. I've been able to remove the two screws holding it in but can't get the unit out. It seems loose but possibly the exterior gear assembly is holding it in. Anyone have this problem? I'm thinking I might be able to take the cover off the unit and release it that way. Any suggestions?
 

lgphilpot

Member
Jul 23, 2013
2
I'm not at all complaining, but I've read this and another page over and over looking for a step by step way to do this. I've gleaned much of probably what I need, but I found it confusing that there were lots of messages in here with related, but not the same problems. My problem is the driver's side actuator, but there are some that don't defrost, some that have a/c on different sides, and I just had trouble following it all and sorting for my specific situation. What is confusing is that some people say the job is a bear, and others say it didn't take that long. There's even a youtube video on this, but he doesn't show you how to remove the dash panel. There's some conflicting... no, confusion (for me) on just how much of the dash has to be removed. Regardless, the information is here and for that I'm grateful.

I just called the local GMC dealer to confirm the part number and just for giggles, I asked them for a price on the repair. She replied, "It will be about $700, plus we'll have to remove and recharge the freon". I knew immediately that I made the right decision to try it myself. She even went so far as to tell me that she'd had people from CarX and Pep Boys call her to ask how to do this repair. Yeah, right. Commissioned salespeople. Thanks, everyone, for this valuable resource!
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
lgphilpot said:
...looking for a step by step way to do this. ...
Welcome! You'll find that everybody has a different process they follow, and it's entirely made up as we go along, to accommodate the size of ones hands, the tools one has in stock, and the amount of time and beer a person takes before they get too frustrated or sloshed to work. There is no one size fits all solution - just dive in! What's the worst that can happen?!?!?!

That said, there are FIVE actuators in there. Each one has a specific purpose. You may be reading threads where people are changing a different actuator than the one you have to. You said you have a problem with the driver's side actuator. The driver's side WHAT actuator? Temp? Airflow mode?

Most of them can be replaced without a total dash removal. Dealers that lie to get you to spend money there are unworthy of your business.

Have you seen this ubiquitous picture I've been posting for years?

allactuators-orig.jpg
 
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lgphilpot

Member
Jul 23, 2013
2
the roadie said:
Welcome! You'll find that everybody has a different process they follow, and it's entirely made up as we go along, to accommodate the size of ones hands, the tools one has in stock, and the amount of time and beer a person takes before they get too frustrated or sloshed to work. There is no one size fits all solution - just dive in! What's the worst that can happen?!?!?!

That said, there are FIVE actuators in there. Each one has a specific purpose. You may be reading threads where people are changing a different actuator than the one you have to. You said you have a problem with the driver's side actuator. The driver's side WHAT actuator? Temp? Airflow mode?

Most of them can be replaced without a total dash removal. Dealers that lie to get you to spend money there are unworthy of your business.

Have you seen this ubiquitous picture I've been posting for years?

allactuators-orig.jpg

Oh, yes. I've studied that to make sure I got the right part. I appreciate that you take the time to help up all out, Roadie! I will keep track of the beers.
 

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,179
Brighton, CO
Hey Roadie.. Had to reset my XUV TailGate, and one of the Actuators died. I have floor, and I have Defrost, but no Vents. Going by your Diagram, that's the Floor/Dash Mode Actuator. Am I reading the correct part # for that of 89018675?

If my other research on this one is correct, this is the Easiest one to replace, being just above the OBD port. Am I correct in this?

I am going to be pulling out my Drivers seat at the same time, to replace the butt warmer. So I should have room to contort...
 

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