Low Pressure Cutout Switch

A low pressure cutout switch is located on the compressor suction line. The low pressure cutout switch opens: -17 to -37 kPa, -0.17 to -0.37 bar, 5 to 11 in. Hg vacuum; closes: 28 to 48 kPa, 0.28 to 0.48 bar, 4 to 7 psig. If the suction pressure becomes too low, the switch opens to stop the compressor.

  • Compressor stops immediately.

  • Evaporator and condenser fans continue normal operation.

  • Compressor will restart if the low refrigerant condition is corrected (switch closes) as long as power is available. The low pressure switch resets (closes) when the pressure increases to 28 to 48 kPa, 0.28 to 0.48 bar, 4 to 7 psig.

Parent topic: Electrical Maintenance

Removal

  1. Disconnect the low pressure cutout switch wires from the control box.

  2. Remove the low pressure cutout switch from the suction line. The fitting on the suction line has a shrader valve which will prevent refrigerant leakage.

      
  1 Low Pressure Cutout Switch
  2 High Pressure Cutout Switch
  3 Discharge Service Valve
  4 Suction Service Valve
     
     

Installation

  1. Install low pressure cutout switch in the suction line.

  2. Route wires into the control box and connect to proper terminals.

  3. Perform a controller pretrip test to verify system operation.

      
  1 Suction Transducer
  2 Discharge Transducer
  3 Suction Service Valve
  4 Discharge Service Valve