Heating/AC all hot or all cold

[zdude]

Mine did this, and I replaced the aspirator above the drivers head since it was getting noisy. That fixed it. Maybe the sensor was going bad itself, not just the fan inside it.
I also had a symptom that the temp control knob seemed to be going bad; the readout was all over the placed as I rotated it. It was sometimes difficult to get it to hot and stay on 90. I would rotate it clockwise to increase the temp, but number would jump all over and actually go back down. Does yours do that too?

If you replace the aspirator, I recommend the actual GM part. I tried 3 Dorman parts from rockauto, and they are noisy as crap. I couldn't stand it, so I finally shelled out the extra $2 for the GM part and it's whisper quiet and know/heat works fine.

 

[tahoe7689]

I have a 2003 tahoe with electronic dual climate zone and at the 60 to 89 degree range it is all cold (like its on 60) and at 90 degrees it very hot. There is no in between. I can switch the air from head to feet to defrost and all those work fine, the only problem is there is no intermediate temperature. I talked to a former mechanic who said it could not be the mix door actuator because the air was changing from head to feet to defrost all fine. This is really been bugging me and I cant seem to figure out the problem

I still have this problem, im on spring break and would love to fix this! I have a long drive from home to college and the all hot/all cold thing really gets annoying........even when the air is off, it still blows some air....

 

[tahoe7689]

I replaced the passenger side blend door actuator with no luck......I can feel it move as I change the temperature on the controls. I have the correct actuator, but I guess it isn't the problem because they both move the same. Can someone please help this is such an annoying problem

 

[tahoe7689]

Mine did this, and I replaced the aspirator above the drivers head since it was getting noisy. That fixed it. Maybe the sensor was going bad itself, not just the fan inside it.
I also had a symptom that the temp control knob seemed to be going bad; the readout was all over the placed as I rotated it. It was sometimes difficult to get it to hot and stay on 90. I would rotate it clockwise to increase the temp, but number would jump all over and actually go back down. Does yours do that too?

If you replace the aspirator, I recommend the actual GM part. I tried 3 Dorman parts from rockauto, and they are noisy as crap. I couldn't stand it, so I finally shelled out the extra $2 for the GM part and it's whisper quiet and know/heat works fine.

I acutally had the dealer diagnose the problem, and thats what they said the problem was. So I just bought the part and did the install myself (saving $260 from the stealership). It worked for a little bit, then went back to all the same problems. I did have the control knob problem, but I just replaced the whole a/c control. Anyways FYI for anyone who has this problem in the future, replace the aspirator over the driver's head (I am assuming mine is having other complications, because it did work for a little bit, and it worked for zdude).

 

[wade]

What is the GM part# for the aspirator?

 

[tahoe7689]

no sure, but I just bought it from the dealer new, and it was $50, the auto parts stores in the area didnt have any kind of aspirator, and I couldnt find any online.

 

[tahoe7689]

Ok, so I am still having the same issue as my original post. I replaced the aspirator and the dealership said the temp sensors in the grille were bad also, so those have been replaced(these sensors also caused my outside temp display in my rearview mirror to freak out but now it's fixed). The dealership reprogrammed the ac control head, but after all the replacement of the aspirator and the two temp sensors, my ac is still all cold or all hot. I really dont want to shell out more money for the stealership to "fix" things. Has anyone found a fix for this problem?

 

[Jbird]

mine only does that on the two driver vents. id really love to know why

 

[tahoe7689]

I hate to resurrect this thread......but I have yet to fix this issue, the same as mentioned above. I finally decided to buy a brand new hvac control module, and replaced the aspirator above the driver's seat. Neither of these fixed the issue....the dealership is speculating a wiring issue...but I don't even know where to begin on the wiring issue. I checked in the headliner and didnt see any obvious frayed wires or loose wires, and the aspirator plug looks good. So in summary, the problems that exist are that my hvac is ice cold from temperature settings on the control from 60-89 (just like on 60 degrees) and all hot on 90, additionally, the rear view mirror flickers on and off like it is being reset (it will flicker on and off like a programming issue, not like its losing power because it flickers on and off displaying all of the leds in the mirror), and I am getting an intermittent aspirator low voltage code. after verifying the aspirator was properly plugged in the code went away, but came back again after a long drive. I have had the outside temperature sensors replaced, so as far as the mirror goes, it could just be a bad mirror, but I thought I would mention it, because I don't know if its related the hvac issue. I would greatly appreciate any help with this issue!

 

[beefcrinkle]

How much does the mirror flicker? (compas/temp go out?)I have noticed that my 03 seems to be cooler in the 69-89 range. and my rear view mirror sometime will flicker, but only when i just started the car. The blend doors work and no aspirator is not making any noise. I am not sure what my issue could be either.

I hate to resurrect this thread......but I have yet to fix this issue, the same as mentioned above. I finally decided to buy a brand new hvac control module, and replaced the aspirator above the driver's seat. Neither of these fixed the issue....the dealership is speculating a wiring issue...but I don't even know where to begin on the wiring issue. I checked in the headliner and didnt see any obvious frayed wires or loose wires, and the aspirator plug looks good. So in summary, the problems that exist are that my hvac is ice cold from temperature settings on the control from 60-89 (just like on 60 degrees) and all hot on 90, additionally, the rear view mirror flickers on and off like it is being reset (it will flicker on and off like a programming issue, not like its losing power because it flickers on and off displaying all of the leds in the mirror), and I am getting an intermittent aspirator low voltage code. after verifying the aspirator was properly plugged in the code went away, but came back again after a long drive. I have had the outside temperature sensors replaced, so as far as the mirror goes, it could just be a bad mirror, but I thought I would mention it, because I don't know if its related the hvac issue. I would greatly appreciate any help with this issue!