Compressor HVAC: Description and Operation
A/C COMPRESSORDenso Compressor -Typical:
Vehicles equipped with the 2.4L gasoline, 2.5L diesel, 2.8L diesel and 3.3L gasoline engines with the front heating-A/C system only, use the Denso 10S17 A/C compressor. Vehicles equipped with the 3.3L and the 3.8L gasoline engines with the optional rear heating-A/C system use the Denso 10S20 A/C compressor. Both A/C compressors include an integral high pressure relief valve. The A/C compressor (Fig. 4) is secured to a mounting bracket on the 2.4L, 2.5L and 2.8L engines and, directly to the cylinder block on the 3.3L and 3.8L engines.
The A/C compressor is driven by the engine through an electric clutch, drive pulley and belt arrangement. The A/C compressor is lubricated by refrigerant oil that is circulated throughout the refrigerant system with the refrigerant.
The A/C compressor draws in low-pressure refrigerant vapor from the A/C evaporator through its suction port. It then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor. The A/C compressor pumps the high-pressure refrigerant vapor to the A/C condenser through the compressor discharge port.
The A/C compressor cannot be repaired and, if faulty or damaged, the entire compressor assembly must be replaced. The compressor clutch, pulley and clutch coil are available for service.
HIGH PRESSURE RELIEF VALVE
A high pressure relief valve is located on the rear of the A/C compressor. This mechanical valve is designed to vent refrigerant from the A/C system to protect against damage to the compressor and other system components, caused by condenser air flow restriction or an overcharge of refrigerant.
The high pressure relief valve vents refrigerant from the A/C system when a discharge pressure of 3445 to 4135 kPa (500 to 600 psi) or above is reached. The relief valve closes when a minimum discharge pressure of 2756 kPa (400 psi) is reached.
The high pressure relief valve vents only enough refrigerant to reduce the A/C system pressure, and then re-seats itself. The majority of the refrigerant is conserved in the A/C system. If the relief valve vents refrigerant, it does not necessarily mean that the valve is faulty.
The high pressure relief valve is a factory-calibrated unit. The relief valve cannot be adjusted or repaired, and must not be removed or otherwise disturbed. The relief valve is only serviced as a part of the A/C compressor assembly.