front cover of the compressor. Be certain that the
snap ring is properly fully and properly seated in the
groove.
(6) If the original clutch plate and clutch pulley
are to be reused, reinstall the original shim(s) on the
compressor shaft against the shoulder. If a new
clutch plate and/or clutch pulley are being used,
install a trial stack of shims 1.0 mm (0.040 in.) thick
on the compressor shaft against the shoulder.
(7) Install the clutch plate onto the compressor
shaft.
(8) Install and tighten the compressor shaft bolt. If
necessary, a band-type oil filter wrench or a strap
wrench can be placed around the clutch plate to aid
in bolt tightening. Tighten the bolt to 17.5 N´m (155
in. lbs.).
NOTE: The shims may compress after tightening
the shaft bolt. Check the air gap in four or more
places to verify the air gap is still correct. Spin the
pulley before performing a final check of the air
gap.
(9) If a new clutch plate and/or clutch pulley are
being installed, the air gap between the clutch plate
and clutch pulley must be checked (Refer to 24 -
HEATING & AIR CONDITIONING/CONTROLS/A/C
COMPRESSOR CLUTCH - STANDARD PROCE-
DURE).
(10) Install the retainer that secures the compres-
sor clutch coil lead to the top of the compressor.
(11) Reconnect the engine wire harness connector
to the clutch coil lead on the top of the compressor.
(12) Reinstall the serpentine accessory drive belt
(Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE
BELTS - INSTALLATION).
(13) Reconnect the battery negative cable.
(14) If a new clutch plate and/or clutch pulley are
being installed, the new clutch components must be
burnished (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/A/C COMPRESSOR CLUTCH
- STANDARD PROCEDURE).
A / C COMPRESSOR CLUTCH
COIL
DIAGNOSIS AND TESTING
A / C COMPRESSOR CLUTCH COIL
The air conditioning compressor clutch coil electri-
cal circuit is controlled by the ATC control module
which is integral to the heater-A/C control. Begin
testing of a suspected compressor clutch coil problem
by performing the ATC Function Test using the
DRBIIItscan tool.PRELIMINARY CHECKS
(1) If no diagnostic trouble codes (DTCs) are found
in the A/C-heater control or the powertrain control
module (PCM), go to Step 2. If any DTCs are found,
repair as required.
(2) If the A/C compressor clutch still will not
engage, verify the refrigerant charge level (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING
- DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM LEAKS). If the refrigerant charge level is
OK, go to TESTS. If the refrigerant charge level is
not OK, adjust the refrigerant charge as required.
TESTS
(1) Verify the battery state of charge (Refer to 8 -
ELECTRICAL/BATTERY SYSTEM/BATTERY -
DIAGNOSIS AND TESTING).
(2) Connect an ammeter (0 to 10 ampere scale
selected) in series with the clutch coil feed terminal.
Connect a voltmeter (0 to 20 volt scale selected) to
measure voltage across the battery and the clutch
coil.
(3) With the A/C-heater control in the A/C mode
and the blower motor at low speed, start the engine
and allow it to run at a normal idle speed.
(4) The A/C compressor clutch should engage
immediately, and the clutch coil supply voltage
should be within two volts of the battery voltage. If
the coil supply voltage is OK, go to Step 5. If the coil
supply voltage is not within two volts of battery volt-
age, test the clutch coil feed circuit for excessive volt-
age drop and repair as necessary.
(5) For the acceptable A/C clutch coil current draw
specifications refer to 24 - HEATING & AIR CONDI-
TIONING - SPECIFICATIONS. Specifications apply
for a work area temperature of 21É C (70É F). If volt-
age is more than 12.5 volts, add electrical loads by
turning on electrical accessories until voltage reads
below 12.5 volts.
(a) If the A/C clutch coil current reading is zero,
the coil is open and must be replaced.
(b) If the A/C clutch coil current reading is above
specifications, the coil is shorted and must be
replaced.
A / C HEATER CONTROL
DESCRIPTION
This ATC system uses a combination of electrical
and mechanical controls. These controls provide the
vehicle operator with a number of setting options to
help control the climate and comfort within the vehi-
cle.
The A/C-heater control is located on the instrument
panel inboard of the steering column and below the
24 - 12 CONTROLS-FRONTVA
