RAM 2500 Van V8-360 5.9L Magnum (1995)
Compressor HVAC: Description and Operation
When the operator selects air conditioning or defrost operation and the A/C low pressure switch, electronic cycling switch, and A/C high pressure switch
are closed, the Powertrain Control Module (PCM) receives an A/C request on circuit C20. Circuit C20 from the high pressure switch connects to cavity
27 of the PCM.
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Circuit C21 connects the A/C select switch to the A/C low pressure switch.
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Circuit C2 connects the A/C low pressure switch to the electronic cycling switch.
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Circuit C22 connects the electronic cycling switch to the A/C high pressure switch. Circuit A21 supplies voltage the electronic cycling switch.
After receiving the A/C request signal, the PCM provides ground for the A/C compressor clutch switch on circuit C13. Circuit C13 connects to cavity 34
of the PCM.
Circuit A21 supplies voltage to the coil side of the relay. In the START or RUN position, the ignition switch connects circuit A1 from fuse 7 in the
Power Distribution Center (PDC) with circuit A21.
Circuit A17 from fuse 3 in the PDC supplies voltage to the contact side of the A/C compressor clutch relay. When the relay contacts close, circuit Al 7
connects to circuit C3. Circuit C3 supplies voltage to the A/C compressor clutch. Ground for the compressor clutch is provided on circuit Z1 which
terminates at the rear of the engine.
The A/C compressor clutch connector has a built-in diode. The diode controls the induced voltage that results from the collapsing magnetic field clutch
disengagement. The diode provides a current path to ground to protect other components and systems.
