Expansion Valve: Description and Operation

Expansion Valve - Description:

The A/C expansion valve controls the amount of refrigerant entering the A/C evaporator and is of a thermostatic expansion valve (TXV) design. The A/C expansion valve consists of an aluminum H-valve type body with an integral thermal sensor and is located at the dash panel between the A/C refrigerant lines and the A/C evaporator.

The A/C expansion valve controls the high-pressure, low temperature liquid refrigerant from the liquid line and converts it into a low-pressure, low temperature mixture of liquid and gas before it enters the A/C evaporator. A mechanical sensor in the A/C expansion valve monitors the temperature and pressure of the refrigerant leaving the A/C evaporator through the suction line, and adjusts the orifice size at the liquid line port to let the proper amount of refrigerant into the A/C evaporator to meet the vehicle A/C cooling requirements. Controlling the refrigerant flow through the A/C evaporator ensures that none of the refrigerant leaving the A/C evaporator is still in a liquid state, which could damage the A/C compressor.

The A/C expansion valve is factory calibrated and cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.