Dodge Dakota (R1). Manual — part 792
NOTE: The air gap is determined by the spacer
shims. When installing an original, or a new clutch
assembly, try the original shims first. When install-
ing a new clutch onto a compressor that previously
did not have a clutch, use 1.0, 0.50, and 0.13 milli-
meter (0.040, 0.020, and 0.005 inch) shims from the
clutch hardware package that is provided with the
new clutch.
(12) To complete the procedure, (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/A/C
COMPRESSOR - INSTALLATION).
A/C COMPRESSOR CLUTCH
RELAY
DESCRIPTION
The a/c compressor clutch relay is a International
Standards Organization (ISO) micro-relay. The termi-
nal designations and functions are the same as a con-
ventional
ISO
relay.
However,
the
micro-relay
terminal orientation (footprint) is different, the cur-
rent capacity is lower, and the relay case dimensions
are smaller than those of the conventional ISO relay.
OPERATION
The compressor clutch relay is a electromechanical
device that switches battery current to the compres-
sor clutch coil when the Powertrain Control Module
(PCM) grounds the coil side of the relay. The PCM
responds to inputs from the a/c heater control, the a/c
loss of charge switch, the a/c pressure transducer and
the evaporator fin probe.
The compressor clutch relay is located in the Power
Distribution Center (PDC) in the engine compart-
ment. Refer to the PDC label for relay identification
and location.
The compressor clutch relay cannot be repaired
and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING - A/C COMPRESSOR
CLUTCH RELAY
RELAY TEST
The compressor clutch relay (Fig. 12) is located in
the Power Distribution Center (PDC). Refer to the
PDC label for relay identification and location.
Remove the relay from the PDC to perform the fol-
lowing tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75 ± 5 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, see the Relay Circuit Test below. If not
OK, replace the faulty relay.
RELAY CIRCUIT TEST
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information).
(1) The relay common feed terminal cavity (30) is
connected to fused battery feed. There should be bat-
Fig. 11 CHECK CLUTCH AIR GAP
1 - FEELER GAUGE
Fig. 12 COMPRESSOR CLUTCH RELAY
TERMINAL LEGEND
NUMBER
IDENTIFICATION
30
COMMON FEED
85
COIL GROUND
86
COIL BATTERY
87
NORMALLY OPEN
87A
NORMALLY CLOSED
24 - 14
CONTROLS
AN
A/C COMPRESSOR CLUTCH (Continued)
tery voltage at the cavity for relay terminal 30 at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is not
used in this application. Go to Step 3.
(3) The relay normally open terminal cavity (87) is
connected to the compressor clutch coil. There should
be continuity between this cavity and the A/C com-
pressor clutch relay output circuit cavity of the com-
pressor clutch coil wire harness connector. If OK, go
to Step 4. If not OK, repair the open circuit as
required.
(4) The relay coil battery terminal (86) is con-
nected to the fused ignition switch output (run/start)
circuit. There should be battery voltage at the cavity
for relay terminal 86 with the ignition switch in the
On position. If OK, go to Step 5. If not OK, repair the
open circuit to the fuse in the junction block as
required.
(5) The coil ground terminal cavity (85) is switched
to ground through the Powertrain Control Module
(PCM). There should be continuity between this cav-
ity and the A/C compressor clutch relay control cir-
cuit cavity of the PCM wire harness connector C
(gray) at all times. If not OK, repair the open circuit
as required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover from the Power Distribution
Center (PDC) (Fig. 13).
(3) Refer to the label on the PDC for compressor
clutch relay identification and location.
(4) Unplug the compressor clutch relay from the
PDC.
INSTALLATION
(1) Install the compressor clutch relay by aligning
the relay terminals with the cavities in the PDC and
pushing the relay firmly into place.
(2) Install the PDC cover.
(3) Connect the battery negative cable.
(4) Test the relay operation.
A/C HEATER CONTROL
DESCRIPTION
The a/c heater control is a completely electronic
control head (Fig. 14). The a/c heater system uses all
electrical controls. These controls provide the vehicle
operator with a number of setting options to help
control the climate and comfort within the vehicle.
Refer to the owner’s manual in the vehicle glove box
for more information on the features, use, and sug-
gested operation of these controls.
OPERATION
The a/c heater control is located to the right of the
instrument cluster on the instrument panel. The a/c
heater control contains a rotary-type temperature
control knob, a rotary-type mode control knob, a rota-
ry-type blower motor speed knob, and push buttons
for a/c compressor and rear window defogger/heated
mirror operation (Fig. 14).
The a/c heater control is fully electronic, contains
the logic and control circuits for the HVAC system,
and is on the J1850 data bus.
The a/c heater control cannot be repaired. If faulty
or damaged, the entire unit must be replaced. The
Fig. 13 POWER DISTRIBUTION CENTER LOCATION
1 - CLIP
2 - BATTERY
3 - TRAY
4 - NEGATIVE CABLE
5 - POSITIVE CABLE
6 - CLIP
7 - FENDER INNER SHIELD
8 - POWER DISTRIBUTION CENTER
Fig. 14 A/C HEATER CONTROL
1 - BLOWER SPEED CONTROL KNOB
2 - TEMPERATURE CONTROL KNOB
3 - MODE CONTROL KNOB
4 - A/C SELECT BUTTON
5 - REAR WINDOW DEFOGGER/HEATED MIRROR SELECT
BUTTON (optional)
AN
CONTROLS
24 - 15
A/C COMPRESSOR CLUTCH RELAY (Continued)
illumination lamps are available for service replace-
ment.
DIAGNOSIS AND TESTING- HEATER-A/C
CONTROL
Satisfactory heater and air conditioner perfor-
mance depends upon proper operation and adjust-
ment of all operating controls and refrigeration
system components. For circuit descriptions and dia-
grams, refer to Air Conditioning/Heater in Group 8W
- Wiring Diagrams. Use of the DRBIII
t is required
for diagnosis and testing, follow instructions on
DRBIII
t.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cluster bezel from the instrument
panel (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - REMOVAL).
(3) Remove the screws that secure the a/c heater
control to the cluster bezel (Fig. 15).
(4) Remove the a/c heater control from the cluster
bezel.
(5) Unplug the wire harness connectors from the
back of the heater-A/C control.
INSTALLATION
(1) Plug the wire harness connector into the back
of the heater-A/C control.
(2) Position the a/c heater control in the instru-
ment panel cluster bezel.
(3) Install the fastener screws and tighten to 2.2
N·m (17 ±3 in. lbs.).
(4) Install the cluster bezel in the instrument
panel (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER - REMOVAL AND INSTALLATION).
(5) Connect the battery negative cable.
(6) Perform A/C cool down test with DRB III.
A/C LOSS OF CHARGE SWITCH
DESCRIPTION
The a/c loss of charge switch is located on the top
of the accumulator. The switch is used to measure if
refrigerant system pressure goes too low. It is not
responsible for cycling the a/c compressor clutch. The
switch is screwed onto an accumulator fitting that
contains a Schrader-type valve, which allows the
switch to be serviced without discharging the refrig-
erant system. The accumulator fitting is equipped
with an O-ring to seal the switch connection.
OPERATION
The loss of charge switch is connected in series
electrically with the Heater-A/C controls between
ground and the Powertrain Control Module (PCM).
The switch contacts open and close causing the PCM
to turn the compressor clutch on and off. This pre-
vents compressor operation when the system charge
is low and prevents damage to the compressor. The
switch opens with a pressure of 7 to 13 psi and closes
when the pressure rises to 15 to 25 psi.
DIAGNOSIS AND TESTING - LOSS OF CHARGE
SWITCH
Before performing diagnosis of the loss of charge
switch, be certain that the switch is properly
installed on the accumulator fitting. If the switch is
too loose it may not open the Schrader-type valve in
the accumulator fitting, which will prevent the
switch from correctly monitoring the refrigerant sys-
tem pressure. Remember that lower ambient temper-
atures during cold weather will open the switch
contacts and prevent compressor operation due to the
pressure/temperature relationship of the refrigerant.
Fig. 15 A/C HEATER CONTROL REMOVE/INSTAL
1 - HEATER A/C CONTROL ELECTRICAL CONNECTOR
2 - HEATER A/C CONTROL
3 - HEATER A/C CONTROL MOUNTING SCREW
24 - 16
CONTROLS
AN
A/C HEATER CONTROL (Continued)
Also verify that the refrigerant system has the cor-
rect refrigerant charge (Refer to 24 - HEATING &
AIR
CONDITIONING/PLUMBING
-
STANDARD
PROCEDURE).
For circuit descriptions and diagrams, refer to Air
Conditioning/Heater in Wiring Diagrams.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the loss of charge switch wire harness
connector from the switch on the accumulator fitting.
(3) Install a jumper wire between the two cavities
of the loss of charge switch wire harness connector.
(4) Connect a manifold gauge set to the refrigerant
system service ports (Refer to 24 - HEATING & AIR
CONDITIONING - DESCRIPTION).
(5) Connect the battery negative cable.
(6) Place the heater-A/C mode control switch knob
in any A/C position and start the engine.
(7) Check for continuity between the two terminals
of the low pressure cycling clutch switch. There
should be continuity with a suction pressure reading
of 48–89 kPa (7–13 psi) or above, and no continuity
with a suction pressure reading of 48–89 kPa (7–13
psi) or below. If OK, test and repair the A/C switch
sense circuit as required. If not OK, replace the
faulty switch.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the wire harness connector from the
loss of charge switch on the top of the accumulator.
(3) Unscrew the loss of charge switch from the fit-
ting on the top of the accumulator.
(4) Remove the O-ring seal from the accumulator
fitting and discard.
INSTALLATION
(1) Lubricate a new O-ring seal with clean refrig-
erant oil and install it on the accumulator fitting.
Use only the specified O-rings as they are made of a
special material for the R-134a system. Use only
refrigerant oil of the type recommended for the com-
pressor in the vehicle.
(2) Install and tighten the loss of charge switch on
the accumulator fitting. The switch should be hand-
tightened onto the accumulator fitting.
(3) Plug the wire harness connector into the loss of
charge switch.
(4) Connect the battery negative cable.
A/C PRESSURE TRANSDUCER
DESCRIPTION
This vehicle is equipped with an a/c pressure
transducer. This transducer is screwed onto a fitting
on the liquid line between the condenser and the
high side refrigerant system service port (Fig. 16).
OPERATION
The main function of the a/c pressure transducer is
to disengage the compressor clutch when the refrig-
erant system high pressures are too high. The PCM
senses a voltage from the transducer and converts it
to a pressure. Based on this pressure, the PCM will
disengage the clutch at 460 psi and re-engage the
clutch at 290 psi. The a/c heater control also uses the
pressure value to operate the auto-recirculation func-
tion for improved a/c performance under extreme
conditions.
DIAGNOSIS AND TESTING - A/C PRESSURE
TRANSDUCER
Before performing diagnosis of the a/c pressure
transducer switch, verify that the refrigerant system
has the correct refrigerant charge. (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING)
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information in Group 8W).
(1) Turn on engine and have a/c selected.
(2) Using the DRBIII
t monitor and record the
pressure value as it is sent out from the PCM.
Fig. 16 A/C PRESSURE TRANSDUCER
1 - HIGH SIDE REFRIGERANT SYSTEM SERVICE PORT
2 - LIQUID LINE
3 - A/C PRESSURE TRANSDUCER
AN
CONTROLS
24 - 17
A/C LOSS OF CHARGE SWITCH (Continued)
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