A/C Cycling Switch
A/C Cycling SwitchNOTE: It is not necessary to recover the refrigerant before removing the A/C cycling switch.
The A/C cycling switch (ACCS) is used to prevent icing of the evaporator core by cycling OFF the A/C compressor clutch when the suction pressure in the low-pressure side of the refrigerant system drops below acceptable levels. The PCM monitors the A/C cycling switch (and dual-function pressure switch on 4.6L and 5.4L vehicles) through the ACCS circuit. When the ACCS circuit is open, the PCM will disengage the A/C compressor clutch.
A/C Pressure Transducer (4.0L)
NOTE: It is not necessary to recover the refrigerant before removing the A/C pressure transducer.
The A/C pressure transducer is used by the PCM to monitor the discharge pressure in the high-pressure side of the refrigerant system. The PCM monitors the A/C pressure transducer through the ACP circuit. When the A/C pressure transducer is reading a discharge pressure above acceptable levels, the PCM will disengage the A/C compressor clutch.
Dual-Function Pressure Switch (4.6L and 5.4L)
NOTE: It is not necessary to recover the refrigerant before removing the dual-function pressure switch.
The dual-function pressure switch includes 2 separate sets of contacts that are opened at 2 different pressures.
The first set of contacts in the dual-function pressure switch is used to interrupt A/C compressor operation in the event of excessively high discharge pressure in the high-pressure side of the refrigerant system. The PCM monitors the first set of contacts in the dual-function pressure switch (and A/C cycling switch) through the ACCS circuit. When the ACCS circuit is open, the PCM will disengage the A/C compressor clutch.
The second set of contacts in the dual-function pressure switch is used by the PCM to engage the high speed cooling fan. The PCM monitors the second set of contacts through the ACP circuit. When the A/C pressure rises above a preset level, the second set of contacts will close and the high-speed cooling fan will be engaged.