I’ve got an issue with my Alero that has me stumped.
So right now where I live the outside air temp is cool, maybe 50 degrees. My car has an AC On/Off button, and a temperature dial. With my AC off, and my temperature dial on full cold, once the car gets warmed up for a few minutes my vents act as if I am in full heat mode blowing hot air. If I nudge the temperature dial one click (it has about 20 positions), suddenly it will start blowing outside temp air. Sometimes it stays this way the whole ride, sometimes it will randomly go back to hot air again, sometimes it will cycle at random intervals. If I nudge the dial sometimes it will fix it quickly, other time I have to nudge it again a few times.
At first I thought it was an AC issue, because I had this happen to me with the AC on when it was a hot day. But my AC can make ice cold air no problem. I checked the refridgerent and its good. With the AC on I get the same symptoms as above, but instead of ambient air I get ice cold air when its working, then randomly heat air. I really feel like the heat level is appropriate for actually being in Heat mode, not just some ambient heat from the car or something.
So I’m pretty stumped. How does the temperature dial work, is it a potentiometer than the computer uses to dictate how much hot or cold air is allowed into the cabin? Is it a mechanical swiper of some sort? I’m very knowledgeable about electronics (my career is an electronics technician), so if its anything to do with that I can fix it, I just don’t know what that knob is actually doing and what other components behind the scenes make it all work. I understand the heat exchanger, the evaporator, how all that works in relation to compressor/refridgerant for cold and engine temp/coolant/thermostat for heat, but no idea what actually happens to only allow one or the other to enter the cabin and why my car is screwed up.
Thanks in advance for any help!