Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hi, my 2009 dodge caliber has an A/C problem, its compressor its not receiving the variable positive voltage at the solenoid. Ground is good. I scanned this car and I got P0645 DTC (A/C Clutch Relay Control Circuit), it's weird because Dodge Caliber does not have an A/C clutch relay. Using my bidirectional scan tool I checked all the sensors and data that have to do with the operation of the A/C compressor, they were Ok. I think I found the problem: I unplugged the A/C pressure sensor wiring and checked one by one its theree wires. I got a good ground, a good 5 volt reference input but my signal wire was reading 5 volts which is interpreted by the PCM as 500 psi high pressure, the ECM will never turn my A/C compressor on. The problem is that this signal wired it's shorted to the 5 volt reference wire inside the electronic board (engine fuse box). I unplugged the C5 connector and the short went off. This is an intermittent fault because when I disconnect the battery I start the car again the air conditioning system works perfectly. I am not sure if the pressure sensor its good, but my question is: If at any moment the sensor fails and send a wrong pressure reading (e.g 5 volts), does this reading got stored at the electronic engine fuse and short my signal wiring? or is it more likely that this board itself is faulty? PD: refrigerant pressures are ok. Thanks for your help. I'll upload the wiring diagrams.
Topic Author
