Workshop Manual

6E–63
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
060R100063
Circuit Description
When air conditioning and blower fan are selected, and if
the system has a sufficient refrigerant charge, a 12-volt
signal is supplied to the A/C request input of the
powertrain control module (PCM). The A/C request
signal may be temporarily canceled during system
operation by the electronic thermostat in the evaporator
case. When the A/C request signal is received by the
PCM, the PCM supplies a ground from the compressor
clutch relay if the engine operating conditions are within
acceptable ranges. With the A/C compressor relay
energized, voltage is supplied to the compressor clutch
coil.
The PCM will enable the compressor clutch to engage
whenever A/C has been selected with the engine running,
unless any of the following conditions are present:
B The throttle is greater than 90%.
B The ignition voltage is below 10.5 volts.
B The engine speed is greater than 4500 RPM for 5
seconds or 5400 RPM.
B The engine coolant temperature (ECT) is greater
than 125 °C (257 °F).
B The intake air temperature (IAT) is less than 5°C
(41°F).
B The power steering pressure switch signals a high
pressure condition.
Diagnostic Aids
To diagnose an the intermittent fault, check for following
conditions:
B Poor connection at the PCM–Inspect connections for
backed-out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal-to-wire connection.
B Damaged harness–Inspect the wiring harness for
damage. If the harness appears to OK, observe the
A/C clutch while moving connectors and wiring
harnesses related to the A/C. A sudden clutch
malfunction will indicate the source of the intermittent
fault.