Air Conditioning Operation

The purpose of the air conditioning (A/C) system is to provide cool air and remove humidity from the interior of the vehicle. The vehicle operator can activate the A/C system in any mode. The A/C system can operate regardless of the temperature setting, however, recirculation is available in any mode other than Defog or Defrost.

Regardless of the selected A/C mode setting, a request is made to the powertrain control module (PCM) to turn on the A/C compressor. The request is sent to the PCM through the A/C request signal circuit from the HVAC control assembly. In order for the PCM to internally ground the A/C clutch relay control circuit, the A/C high and A/C low pressure switches must be closed.

The PCM turns on the A/C compressor by providing a path to ground through the A/C compressor clutch relay control circuit for the A/C compressor clutch relay. Once the relay closes its internal switch, power from the battery is provided to the A/C compressor clutch through the A/C compressor clutch supply voltage circuit. Whenever the compressor is turned off, the A/C compressor clutch diode prevents a voltage spike from entering the vehicles electrical system. The ground circuit provides a pathway to ground for the A/C compressor clutch. The A/C compressor clutch relay control circuit is grounded internally within the PCM.