General Description

Using inputs to both the Powertrain Control Module (PCM) and to the heater and A/C programmer, the PCM controls the compressor clutch. The following components are the inputs to the PCM:
^ The heater and A/C programmer request for the compressor
^ The heater and A/C programmer's A/C possible flag

The following components are the inputs to the heater and A/C programmer:
^ The low refrigerant pressure switch
^ The high refrigerant pressure switch
^ The A/C high side temperature
^ The A/C low side temperature
^ The rear defogger switch (from the Instrument Panel Cluster (IPC))
^ The ambient air temperature
^ The vehicle speed
^ The system mode

The voltage source to the compressor clutch is from the 10 A A/C fuse through the A/C compressor clutch relay which is under PCM control.

When the following inputs to the heater and A/C programmer are at the indicated values, the heater and A/C programmer will signal the PCM that compressor operation is possible:
^ The climate control setting is not OFF or ECON.
^ The outside temperature is above 4°C (40°F).
^ No compressor disabling DTCs are set.

Once engagement is possible, 2 modes of compressor clutch control are available for the minimum time the clutch will stay on. These modes of clutch control are based upon vehicle speed.