A/C Cycling Switch

A/C Pressure Cut-Off Switch:

Air Conditioning Cycling Switch
The Air Conditioning (A/C) cycling switch may be wired to either the ACCS or ACPSW PCM input. When the A/C cycling switch opens, the PCM will turn off the A/C clutch. For information on the specific function of the A/C cycling switch, refer to Climate Control system.

The A/C Cycling Switch (ACCS) circuit to the PCM provides a voltage signal which indicates when the A/C is requested. When the A/C demand switch is turned on, and both the A/C cycling switch and the high pressure contacts of the A/C high pressure switch (if equipped and in circuit) are closed, voltage is supplied to the ACCS circuit at the PCM. Refer to the applicable Wiring Diagram for vehicle specific wiring.

If the ACCS signal is not received by the PCM, the PCM circuit will not allow the A/C to operate. For additional information, refer to PCM outputs, wide open throttle air conditioning cutoff.

Operation
The A/C pressure cut-off switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.
^ The A/C pressure cut-off switch is mounted on a Schrader valve-type fitting on the high pressure side of the A/C pressure cut-off switch.
^ A valve depressor, located inside the threaded end of the A/C pressure cut-off switch, presses on the Schrader valve stem.
^ This allows the A/C pressure cut-off switch to monitor the compressor discharge pressure.
^ When the compressor discharge pressure rises to approximately 2,896 kPa (420 psi), the switch contacts open, disengaging the A/C compressor.
^ When the pressure drops to approximately 1,724 kPa (250 psi), the contacts close to allow operation of the A/C compressor.
^ It is not necessary to discharge the refrigerant system to remove the A/C pressure cut-off switch.

NOTE: The Town Car, Continental, LS6/LS8 and Windstar do not have a dedicated (separate) input to the PCM indicating that A/C is requested. This information is received by the PCM through the BUS + and BUS - (SCP) communication.