set clock CHEVROLET DYNASTY 1993 User Guide

CAUTION: Always install new ring gear bolts. Bolts
must be properly torqued (See Tightening Refer-
ence). After assembling the differential side gears, pinion
gears and pinion gears withthe pinion gear washers,
but without the side gear thrust washers. Rotate the
assembly two full revolutions both clockwise and
counterclockwise. Set up dial indicator as shown and record end play.
Rotate side gear 90 degrees and record another end
play. Again, rotate side gear 90 degrees and record a
final end play. Using the smallest end play recorded, shim that
side gear to within .001 to .013 inch. The other side
gear should be checked using the same procedure.
Fig. 5 Remove or Install Ring Gear Bolts and Ring Gear
Fig. 6 Remove Pinion Shaft Roll Pin
Fig. 7 Remove or Install Pinion Shaft
Fig. 8 Remove or Install Pinion Gears, Side Gears,and Thrust Washers by Rotating Side Gears to Opening in Case
Fig. 9 Differential Gears
21 - 28 TRANSAXLE Ä

CAUTION: See Figure 14 to determine side gear
thrust washer thickness. Side gear end play must be
within.001 to .013 inch.Four select thrust washes are available: .032, .037,
.042, and .047 inch.
Side gear thrust washers are available in 4
select thicknesses: .032, .037, .042, and .047 inch. Measure the depth from the differential case to the
machined surface in 3 places, as shown in Figure 13.
Then measure the height of raised stepon the ring
gear. The difference, minus the proper side gear end
play (.001 to .013 inch) is the proper thrust washer
thickness. For the other side gear: After assembling the differ-
ential side gears, pinion gears, and pinion gears with
the pinion gear washers but withoutthe side gear
thrust washers. Rotate the assembly two full revolu-
tions both clockwise and counterclockwise. Set up dial indicator as shown in Figure 14 and
record end play. Rotate side gear 90 degrees and record another end play. Again, rotate side gear 90
degrees and record a final end play.
Using the smallest end play recorded, shim that side
gear to within .001 to .013 inch.
CAUTION: After reassembly of the differential assem-
bly, insert the inner joint housing spline from a drive
shaft into the side gear. By hand, turn the side gear
with the joint housing spline. If the side gear will NOT
turn, or it feels very tight, remove the ring gear and
install a thinner side gear thrust washer.
Side gear thrust washers are available in four
select thicknesses: .032, .037, .042, and .047 inch.
BEARING ADJUSTMENT PROCEDURE
GENERAL RULES ON SERVICING BEARINGS
(1) Take extreme care when removing and installing
bearing cups and cones. Use only an arbor press for
installation, as a hammer may not properly align the
bearing cup or cone. Burrs or nicks on the bear-
Fig. 12 Differential Gears
Fig. 13 Determine Proper Side Gear Thrust Washer Thickness
Fig. 10 Remove or Install Pinion Shafts
Fig. 11 Remove or Install 4 Pinion Gears and 2 Side Gears
Ä TRANSAXLE 21 - 31

(3) Move selector lever on transaxle one detent
forward from full rearward position. This is selector
2 position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position. (5) Line pressure should read 52 to 58 psi with
throttle lever clockwise and gradually increase, as le-
ver is moved counterclockwise, to 80 to 88 psi. (6) Lubrication pressure should be 10 to 25 psi
with lever clockwise and 10 to 35 psi with lever full
counterclockwise. (7) This tests pump output, pressure regulation,
and condition of rear clutch and lubrication hydrau-
lic circuits.
TEST THREE (SELECTOR IN D)
(1) Attach gauges to lineandkickdown release
ports (Fig. 3). (2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle two detents
forward from full rearward position. This is selector
D position.
(4) Read pressures on both gauges as throttle lever
on transaxle is moved from full clockwise position to
full counterclockwise position. (5) Line pressure should read 52 to 58 psi with
throttle lever clockwise and gradually increase, as le-
ver is moved counterclockwise to 80 to 88 psi. (6) Kickdown release is pressurized only in direct
drive and should be same as line pressure within 3
psi, up to kickdown point. (7) This tests pump output, pressure regulation,
and condition of rear clutch, front clutch, and hy-
draulic circuits.
TEST FOUR (SELECTOR IN REVERSE)
(1) Attach 300 psi gauge to low-reverseport (Fig.
3). (2) Operate engine at 1600 rpm for test.
(3) Move selector lever on transaxle four detents
forward from full rearward position. This is selector
R position.
(4) Low-reverse pressure should read 180 to 220
psi with throttle lever clockwise and gradually in-
crease, as lever is moved counterclockwise to 260 to
300 psi. (5) This tests pump output, pressure regulation,
and condition of front clutch and rear servo hydraulic
circuits. (6) Move selector lever on transaxle to Dposition
to check that low-reverse pressure drops to zero. (7) This tests for leakage into rear servo, due to
case porosity, which can cause reverse band burn
out.
TEST RESULT INDICATIONS
(1) If proper line pressure, minimum to maximum, is
found in any one test, the pump and pressure regulator
are working properly. (2) Low pressure in D, 1, and 2but correct pressure
in Rindicates rear clutch circuit leakage.
(3) Low pressure in D and Rbut correct pressure in
1 indicates front clutch circuit leakage.
(4) Low pressure in R and 1but correct pressure in
2 indicates rear servo circuit leakage.
(5) Low line pressure in all positions indicates a
defective pump, a clogged filter, or a stuck pressure
regulator valve.
GOVERNOR PRESSURE
Test only if transaxle shifts at wrong vehicle speeds
when throttle cable is correctly adjusted. (1) Connect a 0-150 psi pressure gauge to governor
pressure take-off point, located at lower right side of
case, below differential cover (Fig. 3). (2) Operate transaxle in third gear to read pres-
sures. The governor pressure should respond smoothly
to changes in mph and should return to 0 to 3 psi when vehicle is stopped. High pressure at
standstill (above 3 psi) will prevent the transaxle from
downshifting.
THROTTLE PRESSURE
No gauge port is provided for throttle pressure.
Incorrect throttle pressure should only be suspected if
part throttle upshift speeds are either delayed or occur
too early, with a correctly adjusted throttle cable.
Engine runaway on either upshifts or downshifts can
also be an indicator of incorrect (low) throttle pressure
setting, or misadjusted throttle cable. In no case should throttle pressure be adjusted until
the transaxle throttle cable adjustment has been veri-
fied to be correct.
CLUTCH AND SERVO AIR PRESSURE TESTS
A no drive condition might exist even with correct
fluid pressure, because of inoperative clutches or
bands. The inoperative units, clutches, bands, and
servos can be located through a series of tests by
substituting air pressure for fluid pressure (Fig. 4). The front and rear clutches, kickdown servo, and
low-reverse servo may be tested by applying air pres-
sure to their respective passages after the valve body assembly has been removed. To make
air pressure tests, proceed as follows: Compressed air supply must be free of all dirt
or moisture. Use a pressure of 30 psi. Remove oil pan and valve body See Disassembly-
Subassembly Removal .
FRONT CLUTCH
Apply air pressure to front clutch applypassage and
listen for a dull thudwhich indicates that front
Ä TRANSAXLE 21 - 43

so that pump housing and case front may be covered
with soapy solution or water. Leaks are sometimes
caused by porosity in the case or pump housing.If a leak source is located, that part and all associ-
ated seals, O-rings, and gaskets should be replaced
with new parts.
GEARSHIFT LINKAGE ADJUSTMENT
Normal operation of the Park/Neutral Position
Switch provides a quick check to confirm proper
manual linkage adjustment. Move the selector level slowly upward until it
clicks into the ``P'' Park notch in the selector gate. If
the starter will operate the ``P'' position is correct. After checking ``P'' position, move selector slowly
toward ``N'' Neutral position until lever drops in the
``N'' stop. If the starter will also operate at this point
the gearshift linkage is properly adjusted. If the
starter fails to operate in either position, linkage ad-
justment is required.
CAUTION: When it is necessary to disassemble
linkage cable from levers, which use plastic grom-
mets as retainers, the grommets should be replaced
with new grommets. Use a prying tool to force rod
from grommet in lever, then cut away old grommet.
Use pliers to snap new grommet into lever and rod
into grommet.
(1) Set parking brake.
(2) Place gearshift lever in P(PARK) position.
(3) Loosen clamp bolt on gearshift cable bracket.
(4) Column shift: Insure that preload adjustment
spring engages fork on transaxle bracket. (5) Pull the shift lever by hand to the front detent
position (PARK) and tighten lock. Tighten screw to
11 N Im (100 in. lbs.). Gearshift linkage should now
be properly adjusted. (6) Check adjustment as follows:(a) Detent position for neutral and drive should
be within limits of hand lever gate stops. (b) Key start must occur only when shift lever is
in park or neutral positions.
THROTTLE PRESSURE LINKAGE ADJUSTMENT
The throttle pressure cable adjustment is very im-
portant to proper transaxle operation. This adjust-
ment positions a valve which controls shift speed,
shift quality, and part throttle downshift sensitivity.
If the setting is too long, early shifts and slippage be-
tween shifts may occur. If the setting is too short,
shifts may be delayed and part throttle downshifts
may be very sensitive.
CABLE ADJUSTMENT PROCEDURE (4-CYL.)
(1) Perform transaxle throttle pressure cable ad-
justment while engine is at normal operating tem-
perature. (2) Loosen cable mounting bracket lock screw.
(3) Bracket should be positioned with both bracket
alignment tabs touching the transaxle cast surface.
Tighten lock screw to 12 N Im (105 in. lbs.) see Fig-
ure 8.
(4) Release cross-lock on the cable assembly (pull
cross-lock upward) see Figure 7. (5) To insure proper adjustment, the cable must be
free to slide all the way toward the engine, against
its stop, after the cross-lock is released. (6) Move transaxle throttle control lever fully
clockwise, against its internal stop, and press cross-
lock downward into locked position (Fig. 7). (7) The adjustment is complete and transaxle
throttle cable backlash was automatically removed. (8) Test cable freedom of operation by moving the
transaxle throttle lever forward (counterclockwise).
Then slowly release it to confirm it will return fully
rearward (clockwise). (9) No lubrication is required for any component of
the throttle cable system.
ROD ADJUSTMENT PROCEDURE (6-CYL.)
(1) Perform transaxle throttle pressure cable ad-
justment while engine is at normal operating tem-
perature. (2) Loosen adjustment swivel lock screw.
(3) To insure proper adjustment, swivel must be
free to slide along flat end of throttle rod so that pre-
load spring action is not restricted. Disassemble and
clean or repair parts to assure free action, if neces-
sary. (4) Hold transaxle throttle lever firmly toward en-
gine, against its internal stop and tighten swivel lock
screw to 11 N Im (100 in. lbs.)
(5) The adjustment is finished and linkage back
lash was automatically removed by the preload
spring. (6) If lubrication is required see Lubrication,
Group 0.
Fig. 8 Throttle Pressure CableÐTypical
21 - 46 TRANSAXLE Ä

BAND ADJUSTMENT
KICKDOWN BAND (FRONT)
The kickdown band adjusting screw is located on
left side (top front) of the transaxle case. (1) Loosen locknut and back off nut approximately
five turns. Test adjusting screw for free turning in
the transaxle case. (2) Using wrench, Tool C-3880-A with adapter Tool
C-3705, tighten band adjusting screw to 5 N Im (47 to
50 in. lbs.). If adapter C-3705 is not used, tighten ad-
justing screw to 8 N Im (72 in. lbs.) which is the true
torque. (3) Back off adjusting screw the number of turns
listed in Specifications . Hold adjusting screw in this
position and tighten locknut to 47 N Im (35 ft. lbs.)
LOW/REVERSE BAND-REAR
To adjust low-reverse band, proceed as follows:
(1) Loosen and back off locknut approximately 5
turns. (2) Using an inch-pound torque wrench, tighten
adjusting screw to 5 N Im (41 in. lbs.) true torque.
(3) Back off adjusting screw the number of turns
listed under Specifications in the rear of the Tran-
saxle Section in this service manual. (4) Tighten locknut to 14 N Im (10 ft. lbs.).
HYDRAULIC CONTROL PRESSURE ADJUSTMENTS
LINE PRESSURE
An incorrect throttle pressure setting will cause in-
correct line pressure readings even though line pres-
sure adjustment is correct. Always inspect and
correct throttle pressure adjustment before adjusting
the line pressure. The approximate adjustment for line pressure is
1-5/16 inches, measured from valve body to inner
edge of adjusting nut. However, due to manufactur-
ing tolerances, the adjustment can be varied to ob-
tain specified line pressure. The adjusting screw may be turned with an Allen
wrench. One complete turn of adjusting screw
changes closed throttle line pressure approximately
1-2/3 psi. Turning adjusting screw counterclockwise
increases pressure, and clockwise decreases pressure.
THROTTLE PRESSURE
Throttle pressures cannot be tested accurately;
therefore, the adjustment should be measured if a
malfunction is evident. (1) Insert gauge pin of Tool C-3763 between the
throttle lever cam and kickdown valve. (2) By pushing in on tool, compress kickdown
valve against its spring so throttle valve is com-
pletely bottomed inside the valve body. (3) While compressing spring, turn throttle lever
stop screw with adapter C-4553. Turn until head of screw touches throttle lever tang, with throttle lever
cam touching tool and throttle valve bottomed. Be sure
adjustment is made with spring fully compressed and
valve bottomed in the valve body.
VEHICLE SPEED SENSOR PINION GEAR
When the speed sensor is removed for any reason, a
NEW O-ring must be installed on its outside diameter.
REMOVAL AND INSTALLATION
(1) Remove speedometer cable (if so equipped).
(2) Remove harness connector from sensor. Make
sure weatherseal stays on harness connector. (3) Remove bolt securing the distance sensor in the
extension housing. (4) Carefully pull sensor and pinion gear assembly
out of extension housing. (5) Remove pinion gear from sensor.
(6) To install, reverse the above procedure. Make
sure extension housing and sensor flange are clean
prior to installation. Always use a NEW sensor O-ring. (7) Tighten securing bolt to 7 N Im (60 in. lbs.).
Tighten speedometer cable to 4 N Im (35 in. lbs.).
PARK/NEUTRAL POSITION AND BACK-UP LAMP
SWITCH
REPLACEMENT AND TEST
The Park/Neutral switch is the center terminal of the
3 terminal switch. It provides ground for the starter
solenoid circuit through the selector lever in only Park
and Neutral positions. (1) To test switch, remove wiring connector from
switch and test for continuity between center pin of
switch and transaxle case. Continuity should exist only
when transaxle is in Park or Neutral. (2) Check gearshift cable adjustment before replac-
ing a switch which tests bad. (3) Unscrew switch from transaxle case allowing
fluid to drain into a container. Move selector lever to
Park and then to Neutral positions. Inspect to see that
the switch operating lever fingers are centered in
switch opening in the case. (4) Screw the switch with a new seal into transaxle
case and tighten to 33 N Im (24 ft. lbs.). Retest switch
with the test lamp. (5) Add fluid to transaxle to bring up to proper level.
(6) The back-up lamp switch circuit is through the
two outside terminals of the 3 terminal switch. (7) To test switch, remove wiring connector from
switch and test for continuity between the two outside
pins. (8) Continuity should exist only with transaxle in
Reverse position. (9) No continuity should exist from either pin to the
case.
Ä TRANSAXLE 21 - 47

REFRIGERANT SERVICE PROCEDURES INDEX
page page
Adding Partial Refrigerant Charge ............ 10
Charging Refrigerant SystemÐEmpty System . . . 11
Discharging Refrigerant System .............. 11
Evacuating Refrigerant System .............. 11
Manifold Gauge Set Connections ............. 9 Oil Level
............................... 12
R-12 Refrigerant Equipment ................. 8
Refrigerant Recycling ...................... 9
Sight Glass Refrigerant Level Inspection ........ 8
Testing for Refrigerant Leaks ............... 10
SIGHT GLASS REFRIGERANT LEVEL INSPECTION
The filter-drier is equipped with a sight glass (Fig.
1) that is used as a refrigerant level indicator only.
This sight glass is not to be used for A/C perfor-
mance testing. To check the refrigerant level re-
move the vehicle jack. Then clean the sight glass,
start and warm up engine, and hold rpm slightly
above idle (1100 rpm). Place the air conditioning con-
trol on A/C, RECIRC and high blower. The work
area should be at least 21ÉC (70ÉF). If a Fixed Dis-
placement type compressor does not engage, the re-
frigerant level is probably too low for the Low
Pressure Cut-Off switch to detect. Or, with a Vari-
able Displacement compressor, for the Differential
Pressure Cut-off to detect. If compressor clutch does
not engage, test the refrigerant system for leaks. If
compressor clutch engages, allow approximately one
minute for refrigerant to stabilize. View refrigerant
through sight glass. The suction line should be cold
to the touch and the sight glass should be clear.
If foam or bubbles are visible in sight glass, the re- frigerant level is probably low. Occasional foam or
bubbles are normal when the work area temperature
is above 43ÉC (110ÉF) or below 21ÉC (70ÉF). If suction
line is cold and occasional bubbles are visible in the
sight glass, block the condenser air flow. This will in-
crease the compressor discharge pressure. Do not al-
low engine to over heat. Bubbles should dissipate.
If not, the refrigerant level is low.
CAUTION: Do not allow engine to over heat while
blocking the condenser air flow.
WARNING: R-12 REFRIGERANT IS DETRIMENTAL
TO THE ENVIRONMENT WHEN RELEASED TO THE
ATMOSPHERE. DO NOT ADD R-12 REFRIGERANT
TO A SYSTEM THAT HAS A KNOWN LEAK.
The refrigerant system will not be low on (R-12)
unless there is a leak. Find and repair the leak be-
fore charging.
R-12 REFRIGERANT EQUIPMENT
WARNING: EYE PROTECTION MUST BE USED
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE PROCEEDING WITH THIS OPERATION.
PERSONNEL INJURY CAN RESULT.
When servicing an air conditioning system, an A/C
charging station is recommended (Fig. 2). An (R-12)
refrigerant recovery/recycling device (Fig. 3) should
also be used. This device should meet SAE standards.
Contact an automotive service equipment supplier
for refrigerant recycling/recovering equipment. Refer
to the operating instructions provided with the
equipment for proper operation. A manifold gauge set (Fig. 4) must also be used in
conjunction with the charging and/or recovery/recy-
cling device. The service hoses on the gauge set be-
ing used should have manual (turn wheel) or
automatic back flow valves at the service port con-
nector ends. This will prevent refrigerant from being
release into the atmosphere.
Fig. 1 Filter Drier and Sight Glass
24 - 8 HEATING AND AIR CONDITIONING Ä

REFRIGERANT RECYCLING
(R-12) refrigerant is a chlorofluorocarbon (CFC)
that can contribute to the depletion of the ozone
layer in the upper atmosphere. To help protect the
ozone layer, an R-12 recycling device must be used.
Contact an automotive service equipment supplier
for refrigerant recycling equipment. Refer to the op-
erating instructions provided with the recycling
equipment for proper operation.
MANIFOLD GAUGE SET CONNECTIONS
GENERAL INFORMATION
The high pressure (discharge) (RED) hose should
be attached to the 1/4 in. discharge service port. This
port is located on the discharge line between the A/C
compressor and the condenser, or on the high pres-
sure (liquid) line. The low pressure (suction) (BLUE) hose should be
attached to the 3/8 in. suction service port. This port
is located on the air conditioning compressor, or the
suction line between the expansion valve and the
compressor.
SUCTION (LOW PRESSURE) GAUGE CONNECTION
(1) Remove the service port cap from 3/8 in. suc-
tion service port. (2) Check all valves on the equipment being used
to verify they are closed. (3) Inspect the hose gasket in the service port con-
nector at the end of the (BLUE) hose. If the gasket is
flawed, replace it. (4) Thread the hose connector onto the service
port. Quickly secure hose connector to the service
port to avoid loosing refrigerant. To disconnect suction gauge (BLUE) hose:(a) Wrap the end of hose with a shop towel.
(b) Loosen the hose connector.
(c) Push and hold the end of hose toward the ser-
vice port to keep the gasket in contact with service
port. (d) Quickly rotate the connector counterclock-
wise. When the hose connector is completely
Fig. 2 Refrigerant Charging StationÐTypical
Fig. 3 Refrigerant Recovery/Recycling StationÐTypical
Fig. 4 Manifold Gauge SetÐTypical
Ä HEATING AND AIR CONDITIONING 24 - 9

backed off, immediately point the end of hose toward
floor, as possibly trapped refrigerant in the hose will
be released.(e) Install service port cap.
DISCHARGE (HIGH PRESSURE) GAUGE CONNECTION (1) Remove the service port cap from the 1/4 in.
service port. (2) Check all valves on the equipment being used to
verify they are closed. (3) Inspect the hose gasket in the service port con-
nector at the end of the (RED) hose. If the gasket is
flawed, replace it. (4) Use a suitable (3/8 in. male to 1/4 in. female)
adapter (Fig. 5), threaded securely into the end of the
(RED) hose connector.
(5) Thread the 1/4 in. hose adapter connector onto
the service port. Quickly secure adapter connector to
service port to avoid loosing refrigerant. To disconnect the discharge gauge (RED) hose:(a) Wrap the end of hose with a shop towel.
(b) Loosen the hose connector.
(c) Push and hold the end of hose toward the
service port to keep the gasket in contact with service
port. (d) Quickly rotate the connector counterclockwise.
When the hose connector is completely backed off,
immediately point the end of hose toward floor, as
possibly trapped refrigerant in the hose will be
released. (e) Install service port cap.
EVACUATION/RECOVERY/RECYCLING/CHARGING LINE CON-
NECTION
The center manifold (YELLOW) or (WHITE) hose is
used to recycle, recover, evacuate, and charge the
refrigerant system. When the discharge or suction
valves on the manifold gauge set are opened, the
refrigerant in the system will escape through this hose. This hose should be attached to a R-12
Recovery/Recycling device. Refer to the
Recovery/Recycling devices operators manual
for procedures. For disconnection of this hose, refer to Disconnect-
ing the Discharge Gauge (RED) hose in the preced-
ing paragraphs.
TESTING FOR REFRIGERANT LEAKS
If the A/C system is not cooling properly, deter-
mine if the refrigerant system is fully charged with
R-12. Follow the procedures in the Performance Test
Procedures section of this Group. If the refrigerant
system is empty or low in refrigerant charge, a leak
at any line fitting or component seal is likely. To de-
tect a leak in the refrigerant system, perform one of
the following procedures as indicated by the symp-
toms.
EMPTY REFRIGERANT SYSTEM LEAK TEST
CAUTION: Review Safety Precautions and Warnings
in General Information section of this Group.
(1) Evacuate the refrigerant system to the lowest
degree of vacuum possible. (2) Prepare a 10 oz. refrigerant (R-12) charge to be
injected into the system. Refer to Charging Refriger-
ant System for instructions. (3) Connect and dispense 10 ozs. of refrigerant into
the evacuated refrigerant system. (4) Proceed to step two of Low Refrigerant Level
Leak Test.
LOW REFRIGERANT LEVEL LEAK TEST
Caution: Review Safety Precautions and Warnings
in the General Information section of this group.
(1) Using the refrigerant level sight glass, deter-
mine if there is any (R-12) refrigerant in the system. (2) Position the vehicle in a wind free work area.
This will aid in detecting small leaks. (3) Bring the refrigerant system up to operating
temperature and pressure. This is done by allowing
the engine to run for five minutes. (4) With the engine not running, use an Electronic
Leak Detector (or equivalent) and search for leaks.
Fittings, lines, or components that appear to be oily
usually will indicate a refrigerant leak. To inspect
the evaporator core for leaks, it is possible to insert
the leak detector probe into the recirculating air door
opening (Fig. 6).
ADDING PARTIAL REFRIGERANT CHARGE
After all leaks have been corrected and it was not
necessary to empty the refrigerant system, a partial
refrigerant charge can be added.
CAUTION:Review all Safety Precautions and Warn-
ings before attempting to add refrigerant to the sys-
tem. Do not add refrigerant to a system that is
known to have a leak.
Fig. 5 Discharge Hose Adapter
24 - 10 HEATING AND AIR CONDITIONING Ä

(11) Replace shaft hex nut. Tighten the hex nut to 37
N Im (27 ft. lbs.) torque.
(12) Check air gap with feeler gauge (Fig. 12). The
specification is 0.406-0.787 mm (0.016-0.031 inch). If
air gap is not consistent around the circumference,
lightly pry up at the minimum variations. Lightly tap
down at points of maximum variation. The air gap is determined by the spacer shims.
When installing the original or a new clutch
assembly, try the original shims first. When in-
stalling a new clutch onto a compressor that
previously did not have a clutch, use 0.040, 0.020,
and 0.005 shims from the clutch accessory sack. (13) If the air gap does not meet the specification
given, add or subtract shims as required.
COMPRESSOR SHAFT SEAL
Using a refrigerant recovery machine, remove the
refrigerant from the A/C system before replacing
shaft seal.
REMOVAL
(1) Insert the 2 pins of the front plate spanner into
any 2 threaded holes of the clutch front plate (Fig.
1). Hold clutch plate stationary. Remove hex nut
with 19 mm (3/4 inch) socket.
(2) Remove clutch front plate using puller (Fig. 2).
Align puller center bolt to compressor shaft. Thumb
tighten the 3 puller bolts into the threaded holes. (3) Turn center bolt clockwise with 19 mm (3/4
inch) socket until front plate is loosened.
Fig. 12 Check Air Gap
Fig. 1 Hex Nut Removal
Fig. 10 Tool Set Driver
Fig. 11 Front Plate Installation
Ä HEATING AND AIR CONDITIONING 24 - 41

WARNING: AVOID RADIATOR/CONDENSER FAN
BLADES WHEN WORKING IN THE RADIATOR
AREA. FAN IS CONTROLLED BY TEMPERATURE
AND CAN START ANY TIME IGNITION IS ON. PER-
SONAL INJURY CAN RESULT.
(1) Disconnect fan control switch wire connector.
(2) Using a suitable jumper wire, jump across ter-
minals in wire connector. (3) Connect a suitable continuity tester across fan
control switch terminals. (4) Start engine and set idle at 1300 rpm. The ra-
diator fan should run constantly. (5) Set the A/C controls to A/C and high blower.
(6) If the high pressure gauge reads below 1102
kPa (160 psi) there should be no continuity across
the switch terminals.
CAUTION: Do not allow engine to overheat when ra-
diator air flow is blocked.
(7) Block radiator air flow with a suitable cover to
increase the high side pressure to at least 1585 kPa
(230 psi). Electrical continuity should be detected
across the fan control switch terminals. (8) Remove cover from front of vehicle to allow
high side pressure to decrease. When pressure drops
below 1102 kPa (160 psi), continuity should cease. If fan control switch is defective, replace it.
REMOVAL AND INSTALLATION
CAUTION: Refrigerant removal is not necessary
when removing the Condenser Fan Control Switch.
However, a small amount of refrigerant will vent
from the switch port. Review the refrigerant han-
dling section of Safety Precautions and Warnings in
the General Information section of this Group.
(1) Disconnect wire connector from condenser fan
control switch. (2) Loosen and quickly rotate the switch counter-
clockwise and separate from the high pressure line
switch port. To install, reverse the preceding operation.
DIFFERENTIAL PRESSURE CUT-OUT SWITCH
DIAGNOSIS
The Differential Pressure Cut-Out (DPCO) Switch
(Fig. 3) monitors the liquid refrigerant pressure on
the liquid side of the system. The DPCO is located on
the expansion valve. The expansion valve is black in
color when a variable displacement compressor is
used. The DPCO turns off voltage to the compressor
clutch coil when liquid refrigerant pressure drops to
levels that could damage the compressor. The DPCO
is a sealed factory calibrated unit. It must be re-
placed if defective.
DPCO SWITCH DIAGNOSIS
The work area must not be below 10ÉC (50ÉF) to
test the compressor clutch circuit. (1) With gear selector in park or neutral, and park
brake set, start engine and allow to idle. (2) Raise hood and disconnect DPCO switch con-
nector boot. (3) Using a suitable jumper wire, jump across the
terminals inside wire connector boot. (4) If clutch does not engage, the wiring, fuse, re-
lay, ambient switch, or high pressure cut-off switch
can be defective. Refer to Group 8W, Wiring Dia-
grams. (5) If clutch engages, connect a suitable manifold
gauge set. Read low pressure gauge. At pressure 283
kPa (41 psi) and above, DPCO switch will complete
the clutch circuit. If the low pressure gauge reads be-
low 317 kPa (46 psi), the system is low on refrigerant
charge or empty due to a leak. Refer to Testing For
Refrigerant Leaks in the Refrigerant Service Proce-
dures section. (6) Install connector boot on switch and repeat step
number 3. If the clutch does not engage, replace the
DPCO switch.
TEMPERATURE CONTROL CABLEÐAC/AY MODELS
REMOVAL AND INSTALLATION
A Temperature Control Cable is used on non-ATC
heat or heater-A/C systems only. ATC (Automatic
Temperature Control) systems use an electrically op-
erated temperature control. Refer to the ATC section
of this Group. (1) Remove the A/C-Heater control panel assembly.
Refer to A/C-Heater Control Replacement in Group
8E Instrument Panel. Disconnect the cable attaching
flag from the A/C-heater control and remove the ca-
ble from control panel.
Fig. 3 Differential Pressure Cut-Out Switch
24 - 48 HEATING AND AIR CONDITIONING Ä