Heating and Air Conditioning: Description and Operation

GENERAL
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser, the receiver drier, through the evaporator, and back to the compressor.
The refrigerant flow through the evaporator coil is controlled by an internal equalized expansion valve, located inside the evaporator case.
The compressor repeats on and off to maintain the evaporator temperature within a specified range When the evaporator coil temperature falls below a specified point, the thermo control amplifier interrupts the compressor operation. When the evaporator coil temperature rises above the specification, the thermo control amplifier allows compressor operation.
The refrigerant system is protected against excessively high or low pressures by the dual switch, located on the receiver drier. If the system pressure rises above, or falls below the specifications, the dual switch opens to interrupt compressor operation.