High pressures and low pressures can cause severe damage to air-conditioning system components.
High pressure switches are mounted in the high pressure side of the system and have their switch contacts in series with the compressor clutch circuit.
If the pressure exceeds the switch setting, the switch will open circuit the compressor clutch and the compressor will stop circulating refrigerant.
Low pressure switches are mounted in the low pressure side of the system and are also connected in series with the compressor clutch.
Low pressures can occur in air-conditioning systems when the refrigerant has escaped. With no refrigerant flowing lubricating oil flow is also reduced and this can damage the compressor.
Low pressure causes the contacts in the low pressure switch to open and break the electrical supply to the compressor clutch and stop its operation.
