Compressor Clutch Operation: Notes

When both A/C switch and blower switch are selected at A/C-heater control panel, a 12-volt signal is supplied through A/C request input to PCM on 3.2L models (A/C ON input to ECM, on 2.2L models). When A/C request signal is received, under normal engine operating parameters, PCM/ECM supplies ground path for A/C compressor relay. When A/C compressor relay is energized, voltage is applied to compressor clutch coil to engage compressor clutch. A/C request signal may be temporarily canceled by electronic thermostat in evaporator case, to prevent evaporator coil from icing.

On all applications, PCM/ECM will not allow compressor clutch operation if PCM/ECM senses the following operating conditions: throttle position is greater than 90%, ignition voltage less than 10.5 volts, engine speed greater than 4500 RPM, Engine Coolant Temperature (ECT) sensor input more than 257°F (125°C), Intake Air Temperature (IAT) sensor input of 41°F (5°C) or less, and/or Power Steering Pressure Switch (PSPS) sensor signal indicates a high pressure condition.

If compressor is inoperative, ensure none of these operating conditions are present or have influenced compressor clutch operation. If present, repair any faulty conditions as necessary. After repair, check compressor clutch operation.