Air Conditioning: Notes
The A/C refrigerant system is a clutch cycling, thermostatic expansion valve type. The system components are:
- A/C compressor
- A/C clutch
- A/C condenser core
- A/C evaporator core
- Thermostatic expansion valve
- Receiver drier
- Connecting refrigerant lines
The refrigeration system operation is controlled by the:
- Thermostatic expansion valve.
- Evaporator discharge temperature sensor.
- A/C compressor pressure relief valve.
- A/C pressure transducer.
- Powertrain control module (PCM).
- DATA module.
- Ambient temperature sensor.
The refrigerant system incorporates a variable capacity A/C compressor. The A/C compressor clutch engagement is controlled by the vehicle PCM.
The evaporator discharge temperature sensor senses evaporator discharge temperature. The DATC module monitors the evaporator discharge temperature sensor and communicates with the PCM to control clutch cycling. The DATC also monitors the ambient air temperature sensor and disables A/C operation when the ambient air temperature is below 0°C (32°F).
The A/C pressure transducer is located in the compressor discharge line and is monitored by the PCM. If high or low refrigerant pressures are experienced, the PCM will interrupt A/C compressor operation.
The pressure relief valve is installed in the compressor manifold and tube assembly and protects the system from excessively high refrigerant pressure.
The thermostatic expansion valve, which is mounted to the evaporator core inlet and outlet tubes, contains an adjustable orifice which provides the restriction that separates the high and low pressure liquid phases in the refrigeration system.