REFRIGERANT PRESSURE SWITCH CONSTRUCTION
BUE074061503N01
Refrigerant Pressure Switch
• The refrigerant pressure switch is used to interrupt A/C compressor operation in the event of high system discharge pressure.
• The refrigerant pressure switch is mounted on a Schrader valve-type fitting on the high pressure side of the condenser to evaporator line.
• A valve depressor, located inside the threaded end of the refrigerant pressure switch, is used to monitor the compressor discharge pressure.
• It is not necessary to discharge the refrigerant system to remove the refrigerant pressure switch.
• The refrigerant pressure switch has two sets of contacts. One electrical contact is normally closed.
Switch 1
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- When the compressor discharge pressure rises to approx. 3,103 kPa {31.65 kgf/cm2, 450.1 psi}, the switch contacts open, disengaging the magnetic clutch.
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- When the pressure drops to approx. 1,724 kPa {17.58 kgf/cm2, 250.1 psi}, the contacts close to allow operation of the magnetic clutch.
Switch 2
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- The switch contains a second set of electrical contacts used for high-speed fan control.
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- When the compressor discharge pressure reaches approx. 2,241 kPa {22.85 kgf/cm2, 325 psi}, these contacts close and engage the high-speed fan control.
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- When the pressure drops to approx. 1,896 kPa {19.33 kgf/cm2, 275 psi}, the contacts again open and the high-speed fan control is disengaged.
A/C Cycling Switch
• The A/C cycling switch is mounted on Schrader valve-type fitting on the top the accumulator tank.
• A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.
• This allows the suction pressure inside the accumulator tank to control the operation of the A/C cycling switch.
• The electrical switch contacts open when the suction pressure drops to 152-193 kPa {1.550-1.968 kgf/cm2, 22.05-27.99 psi}.
• The contacts close when the suction pressure rises to 276-324 kPa {0.276-0.324 kgf/cm2, 40.03-46.99 psi}.
• When the A/C cycling switch contacts close, the signal to magnetic clutch is sent to the PCM which energizes the A/C relay and supplies B+ voltage to the magnetic clutch.
• When the A/C cycling switch contacts open, the magnetic clutch is deenergized and compressor operation stops.
• The A/C cycling switch will control the evaporator pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.
• This prevents icing of the evaporator and blockage of airflow.
• It is not necessary to discharge the refrigerant system to remove the A/C cycling switch.
