GM OBD Trouble Code 66
A/C Pressure sensor circuit error (low pressure indicated)
The ECM monitors the A/C system pressure sensor circuit. If the system pressure is to low the ECM will not allow the A/C compressor to operate.
Fault Code Description
- 66 - A/C Pressure sensor circuit error (low pressure indicated)
Symptoms
- Poor A/C performance
Common Problems
- Low refrigerant charge due to system leak
- Faulty A/C pressure sensor
- Quick test - On A/C systems with multiple pressure sensors, on a cold engine with the key on and the engine off the scan tool readings for the A/C pressure sensors should all be the same.
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