2002 JEEP GRAND CHEROKEE blower

BLOWER MOTOR
DESCRIPTION
The blower motor and blower wheel are located in
the passenger side end of the HVAC housing, below
the glove box module. The blower motor controls the
velocity of the air flowing through the HVAC housing
by spinning a squirrel cage-type blower wheel within
the housing at the selected speed. The blower motor
and blower wheel can be serviced from the passenger
compartment side of the housing.
OPERATION
The blower motor will only operate when the igni-
tion switch is in the On position, and the a/c heater
mode control switch is in any position, except off. The
blower motor circuit is protected by a fuse in the
junction block. On models with the standard manual
temperature control system, the blower motor speed
is controlled by regulating the battery feed through
the blower motor switch and the blower motor resis-
tor. On models with the optional Automatic Zone
Control (AZC) system, the blower motor speed is con-
trolled by using Pulse Width Modulation (PWM). The
blower motor controller adjusts the battery feed volt-
age to the blower motor, based upon an input from
the blower motor switch, through the AZC control
module. Pulse width modulation of blower power
allows the blower to operate at any speed from sta-
tionary, to full speed.
The blower motor and blower motor wheel cannot
be repaired, and if faulty or damaged, they must be
replaced. The blower motor and blower wheel are
each serviced separately.
DIAGNOSIS AND TESTING - BLOWER MOTOR
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.
For circuit descriptions and diagrams, refer to the
appropriate wiring information. Possible causes of an
inoperative blower motor include:
²Faulty fuse²Faulty blower motor circuit wiring or wire har-
ness connections
²Faulty blower motor resistor (if the vehicle is so
equipped)
²Faulty blower motor controller (if the vehicle is
so equipped)
²Faulty blower motor switch
²Faulty a/c heater mode control switch
²Faulty blower motor.
Possible causes of the blower motor not operating
in all speeds include:
²Faulty fuse
²Faulty blower motor switch
²Faulty blower motor resistor (if the vehicle is so
equipped)
²Faulty blower motor controller (if the vehicle is
so equipped)
²Faulty AZC module (if the vehicle is so
equipped)
²Faulty blower motor circuit wiring or wire har-
ness connections.
VIBRATION
Possible causes of blower motor vibration include:
²Improper blower motor mounting
²Improper blower wheel mounting
²Blower wheel out of balance or bent
²Blower motor faulty.
NOISE
To verify that the blower is the source of the noise,
unplug the blower motor wire harness connector and
operate the HVAC system. If the noise goes away,
possible causes include:
²Foreign material in the HVAC housing
²Improper blower motor mounting
²Improper blower wheel mounting
²Blower motor faulty.
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.
WJDISTRIBUTION 24 - 37

(1) Disconnect and isolate the battery negative
cable.
(2) Pinch the connector retainer and unplug the
blower motor wire harness from the blower motor
(Fig. 2).
(3) Remove the three screws that secure the
blower motor and blower wheel assembly to the
HVAC housing, using either a T-25 Torxthead or
flat-bladed screwdriver.
(4) Lower the blower motor and wheel from the
HVAC housing.
(5) Remove the blower wheel retainer clip (Fig. 3).
(6) Remove the wheel from the blower motor shaft.
INSTALLATION
(1) Press the blower wheel hub onto the blower
motor shaft. Be sure the flat on the blower motor
shaft is indexed to the flat on the inside of the blower
wheel hub.
(2) Install the retainer clip over the blower wheel
hub.
(3) Install the blower motor in the HVAC housing
with three mounting screws. Tighten the mounting
screws to 2.2 N´m (20 in. lbs.).
(4) Plug the blower motor wire harness connector
into the blower motor socket.
(5) Connect the battery negative cable.
DEFROSTER DUCTS
REMOVAL
(1) Remove the instrument panel assembly from
the vehicle(Refer to 23 - BODY/INSTRUMENT
PANEL - REMOVAL).
(2) Remove the three screws that secure the
defroster duct to the HVAC unit housing (Fig. 4).
(3) Remove the defroster duct from the HVAC unit
housing.
Fig. 2 BLOWER MOTOR (HOUSING REMOVED
FROM VEHICLE)
1 - BLOWER MOTOR RESISTOR
2 - BLOWER MOTOR
3 - GROUND STRAP
4 - ELECTRICAL CONNECTORS
5 - HEATER CORE TUBES
Fig. 3 BLOWER MOTOR WHEEL REMOVE/INSTALL
1 - BLOWER MOTOR WHEEL
2 - RETAINER CLIP
Fig. 4 HVAC DEFROSTER DUCT
1 - HVAC UNIT HOUSING
2 - INSTRUMENT PANEL
3 - SCREWS
4 - DEFROSTER DUCT
24 - 38 DISTRIBUTIONWJ
BLOWER MOTOR (Continued)

HVAC HOUSING
REMOVAL
The HVAC housing assembly must be removed
from the vehicle and the two halves of the housing
separated for service access of the heater core, evap-
orator coil, blend door(s), and each of the various
mode doors.
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.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN PLUMBING BEFORE PERFORMING THE
FOLLOWING OPERATION. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - WARNING) (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
CAUTION)
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the instrument panel from the vehi-
cle(Refer to 23 - BODY/INSTRUMENT PANEL -
REMOVAL).
(3) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY)
(4) Disconnect the liquid line refrigerant line from
the evaporator inlet tube(Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING/LIQUID LINE -
REMOVAL) or (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING/LIQUID LINE - REMOV-
AL). Install plugs in, or tape over all of the opened
refrigerant line fittings.
(5) Disconnect the suction line refrigerant line
from the evaporator outlet tube(Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/SUCTION
LINE - REMOVAL), (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING/SUCTION LINE -
REMOVAL) or (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING/SUCTION LINE - REMOV-
AL). Install plugs in, or tape over all of the opened
refrigerant line fittings.(6) Disconnect the heater hoses from the heater
core tubes. Clamp off the heater hoses to prevent loss
of coolant. Refer to Cooling for the procedures. Install
plugs in, or tape over the opened heater core tubes.
(7) If the vehicle is equipped with the manual tem-
perature control system, unplug the HVAC system
vacuum supply line connector from the tee fitting
near the heater core tubes.
(8) Remove the coolant reserve/overflow bottle
from the passenger side inner fender shield. Refer to
Cooling for the procedures.
(9) Remove the Powertrain Control Module (PCM)
from the passenger side dash panel in the engine
compartment and set it aside. Do not unplug the
PCM wire harness connectors. Refer to Electronic
Control Modules for the procedures.
(10) Remove the nuts from the HVAC housing
mounting studs on the engine compartment side of
the dash panel (Fig. 9).
(11) Remove the rear floor heat ducts from the
floor heat duct outlets (Fig. 10).
(12) Unplug the HVAC housing wire harness con-
nectors.
(13) Remove the HVAC housing mounting nuts
from the studs on the passenger compartment side of
the dash panel (Fig. 11).
Fig. 9 HVAC Housing - (rear view)
1 - Instrument Panel
2 - Air Intake
3 - Expansion Valve
4 - HVAC Housing
5 - Heater Core Input/Output Ports
6 - Instrument Panel Wiring Harness
7 - Blower Motor
WJDISTRIBUTION 24 - 41

(8) Release the wire harness electrical connector(s)
from the mounts on the lower case at the blower
motor end of the unit (Fig. 17).
Fig. 13 MODE DOOR ACTUATORS - MANUAL
SYSTEM
1 - VACUUM LINES
2 - ACTUATING LEVERS
3 - LINKAGE
4 - VACUUM ACTUATORS
5 - ACTUATING LEVER
Fig. 14 MODE DOOR ACTUATOR - AZC SYSTEM
1 - LEVER ASSEMBLY
2 - LINKAGE
3 - ELECTRIC ACTUATOR
Fig. 15 REMOVE SCREW WITH PLASTIC WASHER
1 - SCREW WITH PLASTIC WASHER
2 - ELECTRIC ACTUATOR
Fig. 16 HVAC HOUSING CLIPS
1 - ACTUATING LEVERS AND LINKAGE
2 - HOUSING CLIP
WJDISTRIBUTION 24 - 43
HVAC HOUSING (Continued)

(9) Remove the 10 screws that secure the two
housing halves to each other.
(10) Separate the top half of the HVAC housing
from the bottom half (Fig. 18).
Fig. 17 WIRE HARNESS ELECTRICAL
CONNECTOR(S)
1 - BLOWER MOTOR RESISTOR
2 - BLOWER MOTOR
3 - GROUND STRAP
4 - ELECTRICAL CONNECTORS
5 - HEATER CORE TUBES
Fig. 18 HVAC HOUSING- CASE SEPARATED
1 - ELECTRICIAL CONNECTORS
2 - VACUUM ACTUATOR
3 - RECIRCULATION DOOR
4 - THERMAL EXPANSION VALVE
5 - BLOWER MOTOR RESISTOR/CONTROLLER
6 - BLOWER WHEEL
7 - EVAPORATOR AND TUBES
8 - FIN SENSOR PROBE9 - BLEND DOOR
10 - PIVOT SHAFT (MOTOR REMOVED)
11 - PANEL/OUTLET DOOR
12 - LOWER HOUSING
13 - VACUUM ACTUATORS
14 - UPPER HOUSING
15 - VACUUM HARNESS
24 - 44 DISTRIBUTIONWJ
HVAC HOUSING (Continued)

NOTE: The blend door sub-assembly is attached to
the housing with 2 screws, and may be removed for
service (Fig. 19).
ASSEMBLY
(1) Place the top half of the HVAC housing on the
bottom half. Be certain that each of the door pivot
pins align with the pivot holes in the HVAC housing.
(2) Install the 10 screws that secure the two hous-
ing halves to each other. Tighten the HVAC housing
screws to 2.2 N´m (20 in. lbs.).
(3) Attach the wire harness electrical connector(s)
to the mounts on the lower case at the blower motor
end of the unit.
(4) Install the 5 clips that secure the two housing
halves to each other. Check doors for binding after
replacement, and after assembly of housing.
(5) Install the screw with plastic washer holding
the lever assembly to the upper case section.
(6) Install the mode door actuator on the left side
of the housing.
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN PLUMBING BEFORE PERFORMING THE
FOLLOWING OPERATION. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - WARNING) (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
CAUTION)Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Position the HVAC housing to the dash panel.
Be certain that the evaporator condensate drain tube
and the housing mounting studs are inserted into
their correct mounting holes.
(2) Install the HVAC housing mounting nuts to the
studs on the passenger compartment side of the dash
panel. Tighten the nuts to 4.5 N´m (40 in. lbs.).
(3) Connect the HVAC housing wire harness con-
nectors.
(4) Reinstall the rear floor heat ducts to the center
floor heat duct outlets.
(5) Install and tighten the nuts onto the HVAC
housing mounting studs on the engine compartment
side of the dash panel. Tighten the nuts to 7 N´m (60
in. lbs.).
(6) Reinstall the PCM to the passenger side dash
panel in the engine compartment. Refer to Electronic
Control Modules for the procedures.
(7) Reinstall the coolant reserve/overflow bottle to
the passenger side inner fender shield. Refer to Cool-
ing for the procedures.
(8) If the vehicle is equipped with the manual tem-
perature control system, connect the HVAC system
vacuum supply line connector to the tee fitting near
the heater core tubes.
(9) Unclamp/unplug the heater core hoses and
tubes. Connect the heater hoses to the heater core
tubes and fill the engine cooling system. Refer to
Cooling for the procedures.
(10) Unplug or remove the tape from the suction
line and the evaporator outlet tube fittings. Connect
the suction line to the evaporator outlet tube.
Tighten retaining nut to 28 N´m (250 in. lbs.).
(11) Unplug or remove the tape from the liquid
line and the evaporator inlet tube fittings. Connect
the liquid line to the evaporator inlet tube. Tighten
retaining nut to 28 N´m (250 in. lbs.).
(12) Evacuate the refrigerant system. (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING -
Fig. 19 BLEND DOOR SUB-ASSEMBLY (AZC)
1 - PASSENGER SIDE BLEND DOOR
2 - BLEND DOOR SUB-ASSEMBLY
3 - DOOR PIVOT SHAFT BUSHING
4 - DOOR SHAFT LEVER
5 - DRIVER SIDE BLEND DOOR
WJDISTRIBUTION 24 - 45
HVAC HOUSING (Continued)

ready. The refrigerant system should not be left open
to the atmosphere any longer than necessary. Cap or
plug all lines and fittings as soon as they are opened
to prevent the entrance of dirt and moisture. All lines
and components in parts stock should be capped or
sealed until they are to be installed.
All tools, including the refrigerant recycling equip-
ment, the manifold gauge set, and test hoses should
be kept clean and dry. All tools and equipment must
be designed for R-134a refrigerant.
DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM LEAKS
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
If the air conditioning system is not cooling prop-
erly, determine if the refrigerant system is fully-
charged. (Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND TESTING -
A/C PERFORMANCE)
An electronic leak detector designed for R-134a
refrigerant is recommended for locating and confirm-
ing refrigerant system leaks. Refer to the operating
instructions supplied by the equipment manufacturer
for proper care and use of this equipment.
An oily residue on or near refrigerant system lines,
connector fittings, components, or component seals
can indicate the general location of a possible refrig-
erant leak. However, the exact leak location should
be confirmed with an electronic leak detector prior to
component repair or replacement.
To detect a leak in the refrigerant system, perform
one of the following procedures:
SYSTEM EMPTY
(1) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(2) Connect and dispense 0.283 kilograms (0.625
pounds or 10 ounces) of R-134a refrigerant into the
evacuated refrigerant system. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE)
(3) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(4) With the engine not running, use a electronic
R-134a leak detector and search for leaks. Because
R-134a refrigerant is heavier than air, the leak detec-tor probe should be moved slowly along the bottom
side of all refrigerant lines, connector fittings and
components.
(5) To inspect the evaporator coil for leaks, insert
the electronic leak detector probe into the center
instrument panel outlet. Set the blower motor switch
to the lowest speed position, the A/C button in the
On position, and select the Recirculation Mode.
SYSTEM LOW
(1) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(2) Bring the refrigerant system up to operating
temperature and pressure. This is done by allowing
the engine to run with the air conditioning system
turned on for five minutes.
(3) With the engine not running, use a electronic
R-134a leak detector and search for leaks. Because
R-134a refrigerant is heavier than air, the leak detec-
tor probe should be moved slowly along the bottom
side of all refrigerant lines, connector fittings and
components.
(4) To inspect the evaporator coil for leaks, insert
the electronic leak detector probe into the center
instrument panel outlet. Set the blower motor switch
to the lowest speed position, the A/C button in the
On position, and select the Recirculation Mode.
STANDARD PROCEDURE
STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT
WARNING: EYE PROTECTION MUST BE WORN
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED,
BEFORE CONNECTING TO OR DISCONNECTING
FROM THE REFRIGERANT SYSTEM. FAILURE TO
OBSERVE THESE WARNINGS MAY RESULT IN PER-
SONAL INJURY.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
When servicing the air conditioning system, a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 must be used.
Contact an automotive service equipment supplier for
refrigerant recovery/recycling/charging equipment.
Refer to the operating instructions supplied by the
24 - 54 PLUMBINGWJ
PLUMBING (Continued)

(a) If the refrigerant system fails to reach the
specified vacuum, the system has a leak that must
be corrected. (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - DIAGNOSIS AND
TESTING - REFRIGERANT SYSTEM LEAKS)
(b) If the refrigerant system maintains the spec-
ified vacuum for five minutes, restart the vacuum
pump, open the suction and discharge valves and
evacuate the system for an additional ten minutes.
(3) Close all of the valves, and turn off the charg-
ing station vacuum pump.
(4) The refrigerant system is now ready to be
charged with R-134a refrigerant. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
After the refrigerant system has been tested for
leaks and evacuated, a refrigerant charge can be
injected into the system. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - SPECIFICA-
TIONS - CHARGE CAPACITY)
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to charge the refrigerant system with R-134a
refrigerant. Refer to the operating instructions sup-
plied by the equipment manufacturer for proper care
and use of this equipment.
PARTIAL CHARGE METHOD
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
The partial charge method is used to add a partial
charge to a refrigerant system that is low on refrig-
erant. To perform this procedure the evaporator inlet
and outlet tube temperatures are measured. The
temperature difference is measured with a tempera-
ture meter with one or two clamp-on thermocouple
probes. The difference between the evaporator inlet
and outlet tube temperatures will determine the
amount of refrigerant needed.Before adding a partial refrigerant charge, check
for refrigerant system leaks. (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING - DIAGNOSIS
AND TESTING - REFRIGERANT SYSTEM LEAKS)
If a leak is found, make the necessary repairs before
attempting a full or partial refrigerant charge.
(1) Attach a manifold gauge set to the refrigerant
system service ports.
(2) Attach the two clamp-on thermocouple probes
to the inlet and outlet tubes of the evaporator coil.
²If a single thermocouple probe is used, attach
the probe to the evaporator inlet tube just before the
collar of the refrigerant line connector fitting. The
probe must make contact with the bottom surface of
the evaporator inlet tube.
²If dual thermocouple probes are used, attach
probe 1 to the evaporator inlet tube, and probe 2 to
the evaporator outlet tube. Attach both probes to the
evaporator tubes just before the collar of the refrig-
erant line connector fittings. The probes must make
contact with the bottom surfaces of the evaporator
inlet and outlet tubes.
(3) Open all of the windows or doors of the passen-
ger compartment.
(4) Set the A/C button on the A/C Heater controls
to the on position, the temperature control knob in
the full cool position, select Recirculation Mode, and
place the blower motor switch in the highest speed
position.
(5) Start the engine and hold the engine idle speed
at 1,000 rpm. Allow the engine to warm up to normal
operating temperature.
(6) The compressor clutch may cycle, depending
upon ambient temperature, humidity, and the refrig-
erant system charge level.
(7) Hold the engine idle speed at 1,000 rpm.
(8) Allow three to five minutes for the refrigerant
system to stabilize, then record the temperatures of
the evaporator inlet and outlet tubes.
²If a single probe is used, record the temperature
of the evaporator inlet tube. Then remove the probe
from the inlet tube and attach it to the evaporator
outlet tube just before the collar of the refrigerant
line connector fitting. The probe must make contact
with the bottom surface of the evaporator outlet tube.
Allow the thermocouple and meter time to stabilize,
then record the temperature of the evaporator outlet
tube. Subtract the inlet tube temperature reading
from the outlet tube temperature reading.
²If dual probes are used, record the temperatures
of both the evaporator inlet and outlet tubes. Then
subtract the inlet tube temperature reading from the
outlet tube temperature reading.
(9) If the measured temperature differential is
higher than 22É C to 26É C (40É F to 47É F), add 0.4
kilograms (14 ounces) of refrigerant.
24 - 56 PLUMBINGWJ
PLUMBING (Continued)