2010 Camaro SS. My evaporator core fan for the AC system comes on right when I start the car. I have used a bidirectional tool to command the fan off and on. When I command the fan on it turns off, and when I command the fan off it turns on. What could cause the fan to run on high all the time? I have no trouble codes related to the system.
I would start by checking the high speed fan relay by swapping it out with a known good relay. It sounds like it may be stuck closed. The reverse operation with the scan tool my be an indication of a computer glitch but I would make sure the relay is working properly as a first step.
When the vehicle is in the on position, but not started the fan works as normal. When command on it turns on, and off turns off. Once the car starts it behavior is incorrect and starts running continuously. Do you think it might have something to do with the Ac pressure? It's 32 degrees outside and my pressure is 48.7 psi why the system off and the car running.
Check the pressure with the compressor running. It should drop to about 30 psi. if the system is charged correctly.
I evacuated the ac system to rule out the pressure. My vehicle was tuned recently. I went through the tune and compared the changes that were made to my ECU. I noticed that the fan system % in the table had 90 across the board. I flashed the original tune and the fan was acting normal. I've come to the conclusion that the tuners had the fan set to high while the car was on the Dyno in order to keep it cool while they make adjustments to the ECU. I corrected the map table with the previous fan speed and it seems to have corrected my issue.
That makes sense. Good luck.
Old Guys Rule has the answer. Fan relay, about $6 at AutoZone.
