Ranger 4WD L4-153 2.5L SOHC VIN C SFI (2001)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Cycling Switch
The A/C cycling switch is mounted on a Schrader valve-type fitting on the top of the suction accumulator.
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A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.
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This allows the suction pressure inside the suction accumulator to control the operation of the A/C cycling switch.
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The electrical switch contacts open when the suction pressure drops. The contacts close when the suction pressure rises.
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When the A/C cycling switch contacts close, the signal to energize the A/C compressor clutch field coil is sent to the Powertrain Control Module
(PCM). The PCM will then actuate the A/C control relay, energizing the A/C compressor.
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When the A/C cycling switch contacts open, the A/C compressor clutch field coil is de-energized and A/C compressor operation stops.
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The A/C cycling switch will control the evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly
above freezing.
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This prevents icing of the evaporator core and blockage of airflow.
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It is not necessary to discharge the refrigerant system to remove the A/C cycling switch.