I was hoping someone on this forum could help me with this issue. I had to replace my door control module so I removed the door panel and disconnected the electrical connecters attached to it. It was hot outside so I turned the engine on and the AC. After a few minutes I got a check engine light and the AC started blowing hot air. The temp gauge on the dash was reading -44 degrees. I plugged a code reader into the car and the code was P073 (Ambient Air Temperature Failure) I did some research and found out that the thermostat for the air temperature is under the driver's side mirror which had been disconnected when the door panel was removed. So after replacing the door control module and resetting the failure code and putting everything back together the AC won't work. The fan blows and the heater and all the other accessories work but no AC. The compressor does not even try to engage. All the fuses checked OK. Does anyone have an idea of what I screwed up? Help Please! I don't want to have to go get robbed by the dealer. (2010 S80 T6) 50,000 miles.

 

Not sure if this works on newer models, but on older ones disconnecting both battery terminals for 12h seem to reset a couple of things.

 

Got it working. Removed door panel unplugged connectors, put ignition in acc position then turned back off. Plugged connectors back in and AC kicked in and works fine. Not sure if I reset the computer or if there was a bad connection in the connector but anyway its fixed.