The pulley (1) on the A/C compressor drive shaft (4) is driven by the poly-V-belt. The clutch turns on the ball bearing
(3) around the magnetic coil (5) fastened to the A/C compressor housing. The pressure plate (6) with rubber insert
(7) is connected to the A/C compressor drive shaft (4) by splines (8) allowing it to move in the axial direction.

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OPERATION

In order to start operating the refrigerant compressor, the heater A/C control module actuates the electromagnetic
clutch and the solenoid (5) is supplied with electrical current. The magnetic force attracts the pressure plate (6)
against the rubber insert (7) and holds it securely. This creates the connection between the engine and the com-
pressor. If the solenoid (5) is de-energized, then the pressure plate (6) is pressed back by the rubber insert (7) into
its rest position and the connection is interrupted.

The clutch also preforms a safety shutoff of the compressor. To prevent a mechanical defect in the compressor from
causing the accessory drive belt to jump loose, the electromagnetic clutch releases itself automatically. With a
mechanical defect, the compressor rotates more sluggishly or even locks completely. The heat generated at the
friction surface causes the melting fuse (2) in the solenoid (5) to melt. The current supply to the solenoid (5) is
interrupted and the frictional connection is released.

The A/C compressor clutch is not serviced separately. The A/C compressor clutch must be replaced as a unit with
the A/C compressor.

DIAGNOSIS AND TESTING - COMPRESSOR CLUTCH COIL

For circuit descriptions and diagrams, refer to the appropriate wiring diagrams. The battery must be fully-charged
before performing the following tests. Refer to Battery for more information.

1. Connect an ammeter (0 to 10 ampere scale) in series with the clutch coil terminal. Use a voltmeter (0 to 20 volt

scale) with clip-type leads for measuring the voltage across the battery and the compressor clutch coil.

2. With the a/c heater mode control switch in any a/c mode, the a/c heater control a/c switch in the ON position,

and the blower motor switch in the lowest speed position, start the engine and run it at normal idle.

3. The compressor clutch coil voltage should read within 0.2 volts of the battery voltage. If there is voltage at the

clutch coil, but the reading is not within 0.2 volts of the battery voltage, test the clutch coil feed circuit for exces-
sive voltage drop and repair as required. If there is no voltage reading at the clutch coil, use a DRB III

scan tool

and the appropriate diagnostic information for testing of the compressor clutch circuit. The following components
must be checked and repaired as required before you can complete testing of the clutch coil:

•

A/C Heater Control Module Mode Control Switch

•

A/C Pressure Transducer

•

A/C Evaporator Temperature Sensor

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4. The compressor clutch coil is acceptable if the current draw measured at the clutch coil is 2.0 to 3.9 amperes

with the electrical system voltage at 11.5 to 12.5 volts. This should only be checked with the work area temper-
ature at 21° C (70° F). If system voltage is more than 12.5 volts, add electrical loads by turning on electrical
accessories until the system voltage drops below 12.5 volts.

a. If the clutch coil current reading is four amperes or more, the coil is shorted and should be replaced.

b. If the clutch coil current reading is zero, the coil is open and should be replaced.

STANDARD PROCEDURE - COMPRESSOR CLUTCH BREAK-IN

After a new compressor clutch has been installed, cycle the compressor clutch approximately twenty times (five
seconds on, then five seconds off). During this procedure, set the A/C Heater control in the Recirculation Mode, the
A/C button in the on position, the blower motor switch in the highest speed position, and the engine speed at 1500
to 2000 rpm. This procedure (burnishing) will seat the opposing friction surfaces and provide a higher compressor
clutch torque capability.

BLOWER MOTOR REGULATOR

REMOVAL

1. Remove the lower instrument panel cover (2) from

the instrument panel (1). (Refer to 23 - BODY/IN-
STRUMENT

PANEL/INSTRUMENT

PANEL

ASSEMBLY - REMOVAL).

2. Disconnect the blower motor electrical connector

(1) from the relief in the blower motor door.

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