Refrigeration System

REFRIGERATION CYCLE

Refrigerant Flow
The refrigerant flows in the standard pattern, that is, through the compressor, the condenser, orifice tube and/or thermal expansion valve, through the evaporator, the accumulator (from orifice tube), and back to the compressor. The refrigerant evaporation through the evaporator coil is controlled by an orifice tube or an externally equalized expansion valve, located outside the evaporator case.

Freeze Protection
Under normal operating conditions, when the A/C is switched on, the compressor runs continuously, and the evaporator pressure, and therefore temperature, is controlled by the compressor to prevent freeze up.

Refrigerant System Protection

High-pressure switch
The refrigerant system is protected against excessively high pressure by a high-pressure switch, located on the end of the compressor. If the system pressure rises above the specifications, the high-pressure switch opens to interrupt the compressor operation and a set of contacts close to switch the cooling fan on high.

Low-pressure switch
The refrigerant system is protected against excessively low pressure by the low-pressure switch, located on the accumulator. If the system pressure falls below the specifications, the low-pressure switch opens to interrupt the compressor operation. When the outside temperature is below 4 °C (40 °F) the low pressure switch opens to interrupt the compressor operation.

Pressure Relief Valve
The refrigerant system is also protected by a pressure relief valve located on the flexible high pressure hose near the compressor. When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa (38 kg/sq.cm, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere.