AC: Hot on one side, cold on other, pls help?

tealboy · January 16, 2007

Only owned my 04 Z71 Tahoe for 3 months but a problem has developed that I need help with. Suddenly, when the ac is turned on, regardless of the temp setting or mode, cold air comes from the drivers side and very hot air on the passenger. Obviously I tried adjusting the electronic control knob to turn the temp setting down, but it was already on 67 degrees, so i turned it to 60. No change. I turned it off and on, stopped the engine, etc. Nothing.

The only thing i did, which i see no correlation, but i'll mention it anyway, was run a power lead to the back of the truck from the battery to power my electric boat winch. I had to disconnect the battery terminals and run a single wire to the back, but again, i can't imagine how this could have made a difference. A few sparks came from the battery as always when connecting and disconnting.

any ideas? I would apprec the help. no others problems are evident at this time.

Bish · January 16, 2007

Only owned my 04 Z71 Tahoe for 3 months but a problem has developed that I need help with. Suddenly, when the ac is turned on, regardless of the temp setting or mode, cold air comes from the drivers side and very hot air on the passenger. Obviously I tried adjusting the electronic control knob to turn the temp setting down, but it was already on 67 degrees, so i turned it to 60. No change. I turned it off and on, stopped the engine, etc. Nothing.

The only thing i did, which i see no correlation, but i'll mention it anyway, was run a power lead to the back of the truck from the battery to power my electric boat winch. I had to disconnect the battery terminals and run a single wire to the back, but again, i can't imagine how this could have made a difference. A few sparks came from the battery as always when connecting and disconnting.

any ideas? I would apprec the help. no others problems are evident at this time.

<{POST_SNAPBACK}>

Not exactly your symptom but I had to replace the mixer door actuator which was a simple replacement. My heat would stick on high all the time but both sides were hot. Do you have the dual climate for driver and passenger. If NOT, I'm not sure how it can blow different out each side.

tealboy · January 16, 2007

Yes, i have the split climate control whereby the digital temp can be set differently on the driver vs. passenger side.

I was anxious to get home and see the replies to this thread but was surprised by only one response. Perhaps not a common problem.

any help is much appreciated.

Bish · January 16, 2007

Yes, i have the split climate control whereby the digital temp can be set differently on the driver vs. passenger side.

I was anxious to get home and see the replies to this thread but was surprised by only one response. Perhaps not a common problem.

any help is much appreciated.

<{POST_SNAPBACK}>

In that case, I would assume you have 2 mixing doors as opposed to 1 on mine. If that is the case, I bet one of the actuators is not working. About a $20 part IIRC. Just a guess given the door actuator problems well documented on the single zone system.

tealboy · January 18, 2007

can i temporarily shut the door or adjust it so the cold air can flow? It's still hot in florida. BEsides, if i can reach and move the door, it might free it up and start working. Not sure where the door is or whether this can be done, but comments appreciated.

any other input ont he problem from others?

bcampbe7 · May 28, 2007

Sorry to bump a slightly older thread but I am seeing this exact problem.

I just got my Wait4me PCM installed. After installation, the passenger side is hot and the driver's side is cold as it should be. May not have anything to do with the PCM install cause when I switched back to the original I am still getting hot air on the pass. and cold on the driver's.

Another unrelated issue is the sunroof would not slide back. It would open up and close, but not slide back. I turned the car off and back on and it worked fine.

I will give Jesse a call tomorrow to ask him about this PCM.

Lennox · May 28, 2007

Sorry to bump a slightly older thread but I am seeing this exact problem.

I just got my Wait4me PCM installed. After installation, the passenger side is hot and the driver's side is cold as it should be. May not have anything to do with the PCM install cause when I switched back to the original I am still getting hot air on the pass. and cold on the driver's.

Another unrelated issue is the sunroof would not slide back. It would open up and close, but not slide back. I turned the car off and back on and it worked fine.

I will give Jesse a call tomorrow to ask him about this PCM.

Since I have owned my truck '04 bought new, this has happened to me about 5 times. *Usually* I am able to just turn the truck off, and then back on to fix it. Sometimes it takes a few trys.

I am also very curious as to what the problem is as I know it will be permanent before too long (over 80k miles already)

bcampbe7 · May 29, 2007

Since I have owned my truck '04 bought new, this has happened to me about 5 times. *Usually* I am able to just turn the truck off, and then back on to fix it. Sometimes it takes a few trys.

I am also very curious as to what the problem is as I know it will be permanent before too long (over 80k miles already)

I will give that a try...

I only have 37K miles on my 2004.

bcampbe7 · May 29, 2007

Well, mine started working normally today.

I guess starting and stopping the truck a few times is the trick.

MustGoFaster · May 29, 2007

there was a similar problem on whe w-bodys (regal and grand prix) with electronic controls, some turned out to be mechanical problems with actuator motors having stripped gears, but a few (like mine) ran into a programming issue.

to make a long story short- the electronic control units do a self check when power is lost and the computer is reset. (like switching a pcm) to do this, the system cycles the doors. sometimes the actuator gets stuck, but as the system ages and is used, the doors can swing a little "more than usual" this pust the actuator signal out of range for the brain of the controller, and it fubars the thing. it basically swings one blend door one way, and one the other. the result - hot air from one side, cold from the other. apparently this doesnt affect the heat cycle, just the vent and AC.

the downside to this problem - you have to have the brain replaced. IIRC in my old regal it was a $700 fix. (twice) thank god for an extended warranty - paid for itself right there.

it was a major factor in ordering the manual dual controls in my 06. manual controls FTW