QuestionAC was working ok. Shut off engine for a brief errand. On
restart AC not working. AC switch green light on. Compressor
clutch not engaged. No condenser or radiator fan. All fuses,
relays & fuse links ok. No error codes from the ATC self
diagnostic check. Could it just be low refrigerant & Pressure?
AnswerHi, John.
Low refrigerant is one possibility. The A/C compressor and the radiator/condensor fans are all controlled by the engine control module (ECM), which will inhibit A/C operation under any of the following conditions:
1. System pressure too high
2. System pressure too low
3. Engine too hot
4. Evaporator too cold (evaporator temp sensor open)
Since the indicator is coming on, we know the A/C control head is asking the ECM to turn on the A/C. As you simply let the vehicle sit, it's also unlikely that the engine was too hot, the pressure was too high, or the evaporator was too cold.
Considering all this, I'd primarily be checking refrigerant level. Then, if that's okay, I'd be checking the circuit out to be sure the pressure sensor and temp sensor are plugged in. And last, if those items are okay, I'd be checking the wiring itself as well as the ground point for the temp sensor behind the right front inside kick panel.
