Problem with Front HVAC

[tjflemmer]

Both the blend door actuator and the actuator that controls the defrost/vent/floor are not working. I thought it was weird that both actuators would go out at the same time, but I checked all the HVAC fuses and that was the best symptom I could come up with.

I recently replaced the blend door actuator and went through the reset process and nothing has changed. No movement at all on either actuator.

The problem appeared to happen soon after I replaced my factory radio for a new bluetooth stereo. I am wondering if there is some connection required between the harness that controls onstar, etc. and the temperature control module.

Rear HVAC works fine.

Any ideas?

 

[JochenWoern]

Both the blend door actuator and the actuator that controls the defrost/vent/floor are not working. I thought it was weird that both actuators would go out at the same time, but I checked all the HVAC fuses and that was the best symptom I could come up with.

I recently replaced the blend door actuator and went through the reset process and nothing has changed. No movement at all on either actuator.

The problem appeared to happen soon after I replaced my factory radio for a new bluetooth stereo. I am wondering if there is some connection required between the harness that controls onstar, etc. and the temperature control module.

Rear HVAC works fine.

Any ideas?

I HAVE and have had similar problems, changed rear blend door and re-calibrated the actators, the system does WHATEVER it wants.

I have been driving down the freeway with nice ice cold air in the summer, all of a sudden my heater starts to blow HOT air into the cabin. While cruising, I put the truck in NEUTRAL and shut it off, turn it back on and the air blows cold again. WTF?????

Today, just the opposite, now my rear does no longer blow warm/hot, it started to blow cool air into the cabin.

Personnally, I feel the automatic climate control in these trucks is a very bad design and it does not work very well for long. My wife is on her fifth BMW in 15 years, ALL had auto climate control and none EVER failed.

I am starting to HATE this system and I am getting to the point were I am debating if I should park the truck at the GM dealer in order for them to go through it and make it work. With 100 degree summers here, NOT having any AC when needed is not much fun. Not that being cold in the morning on the way to work is any funner.

 

[Longshot]

What did you ever figure out with this. I have the exact same problem and I also replaced the stero.

 

[swathdiver]

Both the blend door actuator and the actuator that controls the defrost/vent/floor are not working. I thought it was weird that both actuators would go out at the same time, but I checked all the HVAC fuses and that was the best symptom I could come up with.

I recently replaced the blend door actuator and went through the reset process and nothing has changed. No movement at all on either actuator.

The problem appeared to happen soon after I replaced my factory radio for a new bluetooth stereo. I am wondering if there is some connection required between the harness that controls onstar, etc. and the temperature control module.

Rear HVAC works fine.

Any ideas?

Get hold of a Tech2 and tell us which codes are being thrown. Then you'll know if a cable is loose/unplugged or which actuator died and why it died. Without those codes your just guessing.

 

[Joao GANDAREZ]

Im hoping some one can help with mine im getting bo229 and b3770 my recirculation door does not work nor the the mode door ordered the mode door but look like a pita to get to the screws. Thanks for any help

 

[Doubeleive]

What did you ever figure out with this. I have the exact same problem and I also replaced the stero.

often the digital a/c controller unit is the problem on the 03-06

 

[swathdiver]

Im hoping some one can help with mine im getting bo229 and b3770 my recirculation door does not work nor the the mode door ordered the mode door but look like a pita to get to the screws. Thanks for any helpView attachment 189855

Now go to your shop manual and see what it says to do with regards to those codes. AllDataDIY is inexpensive and thorough. Curiously, neither of those codes is in my GMT900 manual.

 

[retiredsparky]

Heater comes on – GM
GM has issued a technical service bulletin (TSB) #04-01-38-008 to address AC stops cooling – heater comes on problems with the HVAC system on the following vehicles:

2003-2005 Cadillac Escalade, Escalade ESV, Escalade EXT
2003-2005 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003-2005 GMC Sierra, Yukon, Yukon XL

If it seems that the heating/cooling system in your vehicle has a mind of its own, it’s probably because the wiring harness has rubbed through and is touching metal parts. GM says the actuator harness (actuators are the motors that move the mode and temperature doors) may come in contact with a sharp edge on the instrument panel support brace. Once that happens, it will move and touch the metal, causing the actuators to open and close on their own. And it doesn’t have to be just a change in air temperature. The shorting condition can also change air direction modes, moving air from defrost to vent, etc. If you scan the system, you may see the following trouble codes:

B0229 Recirculation Actuator
B0414 Left Air Temperature Actuator
B0424 Right Air Temperature Actuator
B3770 Mode Actuator

You’ll find the problem area on the left side of the opening in the instrument panel. Inspect it for contact with the support brace and repair any damage you find. Then install a protective cover over the harness and friction tape over the sharp edge of the brace

© 2012 Rick Muscoplat

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Posted on July 28, 2012 by Rick Muscoplat

 

[Joao GANDAREZ]

I replaced both recirculation and mode doors all is well now