In a thermostatic expansion valve system, the components necessary for system operation are:
the condenser, the evaporator, the compressor, the receiver drier, the thermostatic expansion valve, connecting pipes and hoses, a thermostat, blower fans and pressure switches.
The thermostatic expansion valve, also called a TX valve, is located at the entry to the evaporator and provides a throttling or restricting function to control the quantity of refrigerant entering the evaporator. At the same time it must provide for complete vaporization of all the liquid refrigerant which enters the evaporator.
The system is charged with refrigerant and a quantity of lubricating oil which circulates with the refrigerant at all times.
When the air-conditioning system is switched on, an electro-magnetic clutch is energized on the compressor drive plate and the compressor is driven by the engine crankshaft.
Vaporized refrigerant is drawn from the low pressure side of the system by the intake side of the compressor.
It is discharged from the compressor as a high-pressure, high-temperature vapor and flows to the condenser where it is cooled by the air flowing across the condenser coils and fins.
The reduction in temperature causes the refrigerant vapor to condense and turn into a liquid which flows to the receiver drier.
The receiver drier acts as a storage volume for liquid refrigerant and also contains a filter and desiccant or drying material.
The liquid refrigerant must pass through the filter and desiccant to reach the pick-up tube where the refrigerant can flow on to the TX valve.
