05 Tahoe HVAC Hell

[Billard45-70]

New to the foum. Weve got an 05 tahoe LT with aux auto hvac front and rear, hvac code is cj2. I know this topic has been brought up thousands of times in the past, however, ive spent hours reading forums, and i cannot find a thread with the same issue as i am having.

When we got the car everything worked as it should. The resistor, quit so i replaced the resistor and the blower motor, then recalibrated. That fixed my issues, until the blend door actuator quit, after replacing that, i again recalibrated, and everything worked fine again, for about a month. All parts are ac delco

Currently, the air will just barely come out of the vents. The blower motor speeds up and slows down with each speed on the hvac head unit. You can hear the motor is spinning at its highest speed. The mode selections DO change, and switch properly. The only issue is that it doesnt blow hard enough, it takes an hour to defrost the windshield.

Any assistance is much appreciated, we love the car otherwise, but winters coming and we'll have to park it if we cant ge the windows thawed in the morning.

 

[justirv]

New to the foum. Weve got an 05 tahoe LT with aux auto hvac front and rear, hvac code is cj2. I know this topic has been brought up thousands of times in the past, however, ive spent hours reading forums, and i cannot find a thread with the same issue as i am having.

When we got the car everything worked as it should. The resistor, quit so i replaced the resistor and the blower motor, then recalibrated. That fixed my issues, until the blend door actuator quit, after replacing that, i again recalibrated, and everything worked fine again, for about a month. All parts are ac delco

Currently, the air will just barely come out of the vents. The blower motor speeds up and slows down with each speed on the hvac head unit. You can hear the motor is spinning at its highest speed. The mode selections DO change, and switch properly. The only issue is that it doesnt blow hard enough, it takes an hour to defrost the windshield.

Any assistance is much appreciated, we love the car otherwise, but winters coming and we'll have to park it if we cant ge the windows thawed in the morning.View attachment 469881

Starting at basics, are your cabin filters changed out? You mentioned new blower motor and the resistor works (speed adjusts). Any chance of blockage (upstream or downstream) at the blower motor, or that the squirrel cage is slipping on the motor shaft? I believe there are 3 blend door actuators. The bottom one controls temp (cold or heat and easiest to get to). Can you tell if the temp changes from hot to cold (A/C) setting? The middle blend door controls the mode (floor, dash, etc.), and the top one for defrost, IIRC.

 

[Fless]

The blower is a DC motor. SWAG Any chance the voltage polarity is reversed, as would be the motor rotation?

 

[Billard45-70]

Starting at basics, are your cabin filters changed out? You mentioned new blower motor and the resistor works (speed adjusts). Any chance of blockage (upstream or downstream) at the blower motor, or that the squirrel cage is slipping on the motor shaft? I believe there are 3 blend door actuators. The bottom one controls temp (cold or heat and easiest to get to). Can you tell if the temp changes from hot to cold (A/C) setting? The middle blend door controls the mode (floor, dash, etc.), and the top one for defrost, IIRC.

This car does not have a cabin air filter.

With the blower out, i can look up at the intake and i see no blockages of any kind. I tested the blower outside of the housing and everything looks fine there.

My temperature changes as it should, and my defrost works properly as well.

I thought of something just a bit ago; is there any way that the resistor or motor wires could be wired improperly? making the blower motor spin backwards?

 

[justirv]

This car does not have a cabin air filter.

With the blower out, i can look up at the intake and i see no blockages of any kind. I tested the blower outside of the housing and everything looks fine there.

My temperature changes as it should, and my defrost works properly as well.

I thought of something just a bit ago; is there any way that the resistor or motor wires could be wired improperly? making the blower motor spin backwards?

As @Fless stated, could be something to check.

 

[DRLexpress]

Sounds like mine. Will stay tuned to see your outcome. You said you replaced the "resistor", I have not started on mine yet but I thought I read the ones with the auto heads had some kind of module instead of a regular resistor. Am I wrong? The other thing mine does on auto mode the blower never goes to high. On manual mode I can hear it speed up but still not a lot of air movement. Guess I need to research and find were the cabin filter is.

 

[6speedblazer]

sounds like a bad mode door actuator, or something with the mode door. Where does the air come out if its not coming out of the defrost vents? Front vents, floor?

 

[Billard45-70]

sounds like a bad mode door actuator, or something with the mode door. Where does the air come out if its not coming out of the defrost vents? Front vents, floor?

The air DOES come out of the vest as it should, each "mode" works

 

[OR VietVet]

Welcome to the forum from Oregon.

Since you replaced "an actuator" and you said you recalibrated and all was good. Did you try another recalibration? Which actuator was it? When doing the actuator, you may have loosened/messed with some duct work and now has moved enough to cause the problem.

There are some misconceptions out there about the recalibration steps. Which did you follow?

The one I use and has worked for me is as follows:

KOEO and press auto and look for auto on display and set temp at 74 degrees. Then turn key off.

Go in the under hood fuse/relay box and remove the HVAC/ECAS fuse, wait 1 minute and reinstall fuse.

Start engine and if the temp setting has changed, readjust to 74 degrees. Let system recalibrate for 2 minutes, then turn off for 15-20 seconds.

Then restart engine and check to see if all works normal.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[Billard45-70]

Welcome to the forum from Oregon.

Since you replaced "an actuator" and you said you recalibrated and all was good. Did you try another recalibration? Which actuator was it? When doing the actuator, you may have loosened/messed with some duct work and now has moved enough to cause the problem.

There are some misconceptions out there about the recalibration steps. Which did you follow?

The one I use and has worked for me is as follows:

KOEO and press auto and look for auto on display and set temp at 74 degrees. Then turn key off.

Go in the under hood fuse/relay box and remove the HVAC/ECAS fuse, wait 1 minute and reinstall fuse.

Start engine and if the temp setting has changed, readjust to 74 degrees. Let system recalibrate for 2 minutes, then turn off for 15-20 seconds.

Then restart engine and check to see if all works normal.

Thats is the procedure that i followed, and have tried multiple times. I replaced the blend door actuator for the drivers side, so no ductwork was removed. I should also add, with the blower running, i do not feel leaks throughout the duct work, at least not anywhere i can fit my hand to feel

 

[Fless]

I may have missed it, but does this happen when you're not using the HVAC head in AUTO mode? Does it do the same in manual mode?

 

[Billard45-70]

It does the same in auto or manual

I may have missed it, but does this happen when you're not using the HVAC head in AUTO mode? Does it do the same in manual mode?

 

[bcbickers]

New to the foum. Weve got an 05 tahoe LT with aux auto hvac front and rear, hvac code is cj2. I know this topic has been brought up thousands of times in the past, however, ive spent hours reading forums, and i cannot find a thread with the same issue as i am having.

When we got the car everything worked as it should. The resistor, quit so i replaced the resistor and the blower motor, then recalibrated. That fixed my issues, until the blend door actuator quit, after replacing that, i again recalibrated, and everything worked fine again, for about a month. All parts are ac delco

Currently, the air will just barely come out of the vents. The blower motor speeds up and slows down with each speed on the hvac head unit. You can hear the motor is spinning at its highest speed. The mode selections DO change, and switch properly. The only issue is that it doesnt blow hard enough, it takes an hour to defrost the windshield.

Any assistance is much appreciated, we love the car otherwise, but winters coming and we'll have to park it if we cant ge the windows thawed in the morning.View attachment 469881

I don't know if this is your issue, but I have a similar problem with non-OEM AC control units. The LEDs are out on my factory controls, and the temperature knob resistors don't work correctly (temp setting jumps around up and down, and you have to keep turning the knob until you hopefully get the temp setting you want). The OEM part is discontinued, so I had to go with an aftermarket replacement. I have tried two different control units, both with the same results: the blower motor doesn't blow much air out at all. Like you mentioned, the blower motor spins up and down with commanded fan speeds, but it doesn't spin as fast or blow as hard as my factory controls. Full fan speed on the aftermaket unit is like fan setting two on my factory unit. Part number match, plug and screw holes line up perfectly. It just doesn't put out as much air.

I linked below one of the units I bought. The main difference I can tell is the font of the Auto button. It's a little different than my factory unit. Not sure if this is your problem, but it may be something to check. Good luck!

AC Heater Climate Control Module 599-211XD For Chevy GMC Improved Design | eBay

Seamless fit, unit is identical in appearance to the factory module, retaining look and feel. For GMC Envoy 2002-2009. For GMC Envoy XL 2002-2006. For GMC Envoy XUV 2004-2005. For GMC Sierra 1500 2003-2006.

www.ebay.com