Air Conditioning System Overview

The refrigerant system components include the following:

• Pulley driven A/C compressor and clutch assembly (non-hybrid)
• Electric A/C compressor (hybrid)
• A/C compressor clutch assembly (non-hybrid)
• A/C condenser core
• A/C evaporator core
• Receiver/drier
• Connecting refrigerant lines
• Thermostatic Expansion Valve (TXV)

The refrigerant system incorporates an A/C compressor controlled by the PCM through an A/C clutch relay. The HVAC module sends an A/C request signal to the Instrument Cluster (IC), which relays the request to the PCM. An evaporator discharge air temperature sensor is used to cycle the A/C compressor off when the evaporator core temperature falls below an acceptable temperature.

The HVAC module will send an A/C request signal to the IC  if the ambient temperature is above approximately 35°F (2°C) and any one of the following conditions are met:

• A mode which requires A/C operation has been manually selected by the driver.
• The driver selects the A/C button while operating in manual mode.
• A/C is operating automatically via AUTO mode and the driver has not deselected A/C operation.

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

• The evaporator discharge air temperature sensor is reading an acceptable temperature.
• The low-charge protection switch is not open due to excessively low refrigerant pressure.
• The A/C pressure transducer is reading an acceptable pressure in the high-pressure side of the refrigerant system.
• The engine coolant temperature is not excessively high.
• The PCM has not detected a Wide Open Throttle (WOT) condition.

An A/C pressure relief valve is installed to protect the refrigerant system against excessively high refrigerant pressures.

Refrigerant flow into the evaporator core is metered by a TXV  .