Pressure Switch Assembly
The pressure switch assembly is located in the accumulator and comprises the following:
Low pressure safety switch
High pressure safety switch
Low pressure safety switch
The low pressure safety switch is provided to protect the compressor from damage, resulting from insufficient lubrication. The lubricant is normally carried through the system by the refrigerant, therefore, loss of refrigerant will result in loss of lubricant. A low pressure in the high pressure part of the system can be caused by leakage of refrigerant to atmosphere, though extremely low ambient temperatures can also cause low pressure in this part. Consequently, when the pressure in the accumulator falls to 180 kPa (1.8 bar), the low pressure switch opens to switch off the air conditioning system. When the pressure rises to 190 kPa (1.9 bar), the switch closes to enable the air conditioning system to operate.
High pressure safety switch
The high pressure safety switch is provided to protect the air conditioning system from pressures above 2940 kPa (29 bar). At this pressure, the switch opens to switch off the air conditioning system. When the pressure falls to 2350 kPa (23 bar), the switch closes to switch on the air conditioning system. Causes of excess pressure can be restriction of air flow through the condenser, malfunction of an auxiliary fan, or unusually high ambient temperatures.