Pinpoint Test O : The Air Conditioning (A/C) Is Inoperative: Notes

Refer to Manual Climate Control System , for schematic and connector information.

Refer to Automatic Climate Control System , for schematic and connector information.

Normal Operation and Fault Conditions 

An accurate evaporator temperature is critical for compressor engagement. The PCM uses the temperature measurement to turn the A/C compressor off before the evaporator temperatures are cold enough to freeze the condensation on the evaporator core.

When an A/C request is received by the PCM, the A/C compressor clutch only engages through the A/C clutch relay if all of the following conditions are met:

• The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
• The PCM does not detect excessively high engine coolant temperature.
• The PCM does not detect an ambient air temperature below 0 °C (32 °F).
• The PCM has not detected a WOT condition.
• The HVAC control module does not detect an evaporator discharge air temperature below 1 °C (33.8 °F).

Possible Sources 

• Fuse
• Wiring, terminals or connectors
• A/C system discharged or low refrigerant charge
• Network concerns
• Evaporator temperature sensor
• A/C pressure transducer
• A/C compressor clutch field coil
• A/C compressor clutch air gap
• A/C clutch relay
• HVAC control module