PT Cruiser L4-2.4L (2008)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Low Pressure Switch
Description
DESCRIPTION
The A/C low pressure switch (1) sends a signal to the powertrain control module (PCM) or engine control module (ECM) (depending on engine
application) to regulate the refrigerant system pressure and control A/C evaporator temperature by turning the A/C compressor clutch off and on See:
Compressor HVAC/Compressor Clutch/Description and Operation/Operation.
The A/C low pressure switch is mounted on a fitting located on the top of the A/C accumulator. The fitting is equipped with an O-ring seal and
Schrader-type valve.
The A/C low pressure switch can be serviced without discharging the refrigerant system.
Operation
OPERATION
The A/C low pressure switch is electrically connected in series with the A/C-heater control and the A/C high pressure switch, between ground and the
powertrain control module (PCM) or the engine control module (ECM) (depending on engine application) or the gateway module if equipped with the
1.6L engine.
The A/C low pressure switch contact opens or closes the path the ground, allowing the PCM/ECM to turn the A/C compressor clutch on and off. This
regulates the refrigerant system pressure and controls A/C evaporator temperature. Controlling the evaporator temperature prevents condensate water on
the evaporator fins from freezing and obstructing A/C system air flow.
The A/C low pressure switch contacts are open when the A/C suction line pressure is approximately 152 kPa (22 psi) or lower. The A/C low pressure
switch contacts will close when the A/C suction line pressure rises to approximately 234 to 262 kPa (34 to 38 psi) or above. Lower ambient
temperatures, below approximately -1° C (30° F), will also cause the A/C low pressure switch contacts to open due to the pressure/temperature
relationship of the refrigerant in the system.
The A/C low pressure switch is factory-calibrated and cannot be adjusted or repaired and must be replaced if found inoperative or damaged.
