This past June my A/C started to blow warm air even if I had it on max cool. Took it to the dealer and they said it was the compressor failing. They vacuumed and recharged the system and I was getting cold air again. Fast forward to last week, and the same symptoms popped up. And the system was blowing warm air. Yesterday I stopped on the way home, restarted the car and the A/C was blowing cold air again.

If the compressor was failing would it not work at all? I would hate to replace the compressor and find out later it was something else.

Maybe related but the outside temperature reading is higher than it should be.

Thanks

 

The first thing to check again is the refrigerant pressure. You might have a leak. There is a pressure/temp switch in the front condenser. If pressure is low it shuts down the system to protect the compressor. If borderline a reboot by restarting might restore operation briefly but it will go back into protection mode.

You cannot diagnose anything on these HVAC systems without correct refrigerant pressure.