Sable V6-3.0L VIN U (1999)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Pressure Cutoff Switch
General Information
An A/C pressure cut-off switch is used on all vehicles to interrupt operation of the A/C compressor in the event of high system discharge pressures.
The A/C pressure cut-off switch is located in the A/C manifold and tube between the A/C compressor and the A/C condenser core.
Dual Function
The A/C pressure cut-off switch has two sets of contacts. One electrical contact is normally closed.
-
When compressor head pressure rises to 2860-3068 kPa (415-445 psi), the contacts open and the compressor operation is shut off.
-
When head pressure drops to 1517-1930 kPa (220-280 psi), the contacts again close and allow operation of the A/C compressor.
-
Shutting down compressor operation prior to the pressure relief valve set point of 3103 kPa (450 psi) makes sure refrigerant is contained in
the A/C system.
The switch contains a second set of electrical contacts for high-speed fan control which are normally open.
-
When discharge line pressure reaches 1965-2172 kPa (285-315 psi), these contacts close and engage the high-speed fan control.
-
When pressure drops to approximately 1724 kPa (250 psi), the contacts again open and the high-speed fan control is disengaged.
With Electronic Automatic Temperature Control
An A/C pressure cut-off switch:
-
is used to interrupt A/C compressor operation in event of high system discharge pressures.
-
is located on the A/C manifold and tube between the A/C compressor and the A/C condenser core.
-
has two sets of contacts. One electrical contact is normally closed.
The A/C pressure cut-off switch operates as follows:
-
When compressor head pressure rises to approximately 2860-3068 kPa (414-445 psi), the contacts open and the compressor operation is shut off.
-
When head pressure drops to approximately 1517-1930 kPa (220-280 psi), the contacts again close and allow operation or the A/C compressor.
-
Shutting down compressor operation prior to the pressure relief valve set point of 3103 kPa (450 psi) makes sure the refrigerant is contained in the
A/C system.
The switch contains a second set of normally open electrical contacts for the engine cooling fan motor.
-
When discharge line pressure reaches approximately 2137-2344 kPa (310-340 psi), these contacts close and engage the engine cooling fan motor
as override of the engine cooling system.
-
When pressure drops to approximately 1896 kPa (275 psi), the contacts again open and the fan motor is disengaged. Fan control is returned to the
powertrain control module.
