I have a 2002 Monte Carlo SS with dual climate control. Recently I've started having issues with passenger side temperature control. I had the a/c checked and it's charged and working correctly. While running A/C the pass. side will suddenly turn hot. I can slide pass. side control up to heat, pause for a second and slide it back down and sometimes it will go back to blowing cold air. I've noticed while sliding the lever down , if I go all the way down it doesn't get me cold air. Therefore I have to stop a couple notches above max cold. Some times i have to do it 7-8 times to get it to change back. It will usually hold then till next time, other times it will fall back to heat after a while. I've read through the forums and haven't come across this exact scenario or haven't done the right search. I'm looking for a way to diagnose what is causing the problem. if you have any suggestions or need more information please feel free to drop me a line.Thank you in advance.

 

That does sound like the actuator if it's randomly changing on you.

 

My passenger side is blowing hot as well. I'm going to change the actuator door tomorrow. A year ago I replaced the climate control when the fan control stopped working and I went from dual settings (two tabs) to a single setting (a dial) for both sides. I'm a bit confused how one side is out with a single dial and one actuator door but I'll find out if its the actuator door tomorrow. Did you fix yours?

 

Hi; This is just my two cents, I could be wrong, so research this for your year car!....but i've read where removing the fuse controlling the hvac system with the ignition off, then waiting over 60 seconds, then reinstalling the fuse, then letting the car's ignition sit for another 60+ seconds, then energising the ignition and turning on the climate controls, will reboot/recalibrate the system, by the computer... I haven't tried this out yet myself, i've only read about this "fix" elsewhere. I plan to, when I install a rebuilt blend door actuator on my drivers side, 07 SS Monte Carlo. It couldn't hurt anything to try! Computers are just as likely the culprit as anything else. You know those "tankless" water heaters they sell for homes? I've never replaced one part in them...( i'm a retired plumbing contractor/journeyman plumber). I would simply unplug them and wait for about 5 minutes, then, I would plug them back in. That's it! they would fire right up and work fine....Never once did I have a customer call me back out for the same problem....What would happen was, the trouble codes would "pile up" and after some time, the computer couldn't function normally anymore and would then just shut down!....I would only charge them a fraction of my hourly rate..in case you were wondering...My point is, the computer maybe just needs to calibrate the hvac system over again from scratch, back to default factory settings...I read about doing what I described from this forum....PS, On youtube, there's an AC Delco video that "tells you" that the only way to recalibrate your hvac systems blend door actuators, is by their (i'm sure) very expensive diagnostic reprogramming procedure..yeah, nice try GM ! I'll try the fuse thing first....good luck gentleman!!