Dakota 4WD V8-4.7L Flex Fuel (2008)
Compressor Clutch Relay: Description and Operation
Operation
OPERATION
The A/C clutch relay is an electromechanical switch that uses a low current input controlled by the powertrain control module (PCM) to control the high
current output to the A/C clutch field coil. The movable, common feed relay contact is held against the fixed, normally closed relay contact by spring
pressure. When the electromagnetic relay coil is energized, it draws the movable common feed relay contact away from the fixed, normally closed relay
contact and, holds it against the fixed, normally open relay contact. This action allows high current to flow to the A/C clutch field coil.
When the relay coil is de-energized, spring pressure returns the movable relay contact back against the fixed, normally closed contact point. The resistor
or diode is connected in parallel with the relay coil, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the
electromagnetic field of the relay coil collapses.
The A/C clutch relay terminals are connected to the vehicle electrical system through a receptacle in the integrated power module (IPM). The inputs and
outputs of the A/C clutch relay include:
-
The common feed terminal (30) receives fused battery current through a B(+) circuit at all times.
-
The coil ground terminal (85) receives a ground input from the PCM through the A/C clutch control circuit only when the PCM electronically
pulls the control circuit to ground.
-
The coil battery terminal (86) receives fused battery current through the ignition switch circuit only when the switch is in RUN.
-
The normally open terminal (87) provides a battery current output to the A/C clutch coil through the A/C clutch relay output circuit only when the
compressor clutch relay coil is energized.
-
The normally closed terminal (87A) is not connected to any circuit in this application, but provides a battery current output only when the A/C
clutch relay coil is de-energized.
The A/C clutch relay cannot be repaired must be replaced if found inoperative or damaged. Refer to the appropriate wiring information for diagnosis and
testing of the ISO-standard relay and for complete HVAC wiring diagrams.
