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A/C Gompressor Controls (conrd)
- How the Circuit Works
Battery voltage is supplied through fuse 56 to the
A,/C compressor clutch relay contacts at all times.
With the ignition switch in ON (ll), voltage is applied
to the coil of the A,/C compressor clutch relay
through fuse 17. When you push the A,/C switch
ON, and the heater fan switch is in posation 1, 2, 3,
or 4, a "ground" input is provided to the engine or
powertrain control module (ECM or PCM) through
the A,/C thermostat and the A,/C pressure switch.
The A,/C compressor clutch relay is grounded by the
engine or powertrain control module (ECM or PCM).
When energized, the A,/C compressor clutch relay
allows battery voltage to turn on the A,/C
comDressor clutch,
The A,/C ON indicator light comes on when the A"/C
system is requested.
A,/C Thermostat
The A,/C thermostat is located on the evaoorator
housing. The AJC thermostat turns off the A,/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. The blower motor will keep running
when the sensor lurns off the compressor.
A,/C Pressure Switch
The A,/C pressure switch is located in the condenser
outlet line where refrigerant is in a high
temperature/high
pressure liquid state. The switch
will sense abnormally high or low pressure, and
open the circuit. This removes ground, and the
compressor will stop running.
Refer to the Service Manual (Section 22,
Air Conditioning)
for specific tests or
troubleshooting
procedures.
62-2
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Table of Contents
Troubleshooting
