cooling JEEP CHEROKEE 1994 Service Owners Manual

SERVICE DIAGNOSISÐELECTRICAL
BLOWER CONTROLSÐXJ VEHICLES
DESCRIPTION
The blower motor delivers air to the inside of the
vehicle. Its speed is controlled by the blower switch
and the blower resistors. With the switch in LO, part
of the battery voltage is supplied to the motor
through all of the resistors. The motor runs slowly.
As the blower switch is moved to a higher speed, the
switch allows more voltage to be applied to the
blower motor, which will increase its speed. When
the switch is in HI, the blower resistors are bypassed
and battery voltage is applied directly to the blower
motor. The motor runs at the fastest speed in this
mode.
DIAGNOSIS
Refer to the Group 8W, Wiring Diagrams for com-
plete system schematic.
1. BLOWER MOTOR INOPERATIVE
²Remove and inspect fuse. If the fuse is blown, re-
place fuse.
2. BLOWER MOTOR INOPERATIVE (HI Posi-
tion)
Put the ignition switch in RUN, the select switch
in HEAT and the blower switch on HI.
²Blower motor connector (Terminal A) should be
battery voltage. If not go to next step.
²Blower motor connector (Terminal B) should be 0
ohms. If not, repair wire to ground.
²Blower switch connector (Terminal C) should be
battery voltage. If battery voltage replace blower
switch. If not, replace select switch.
3. BLOWER MOTOR INOPERATIVE (LO, M1
& M2 Positions)
Ignition switch in RUN, select switch in HEAT.
²Blower resistors connector (Terminal D) should be
battery voltage. If not, replace select switch.
²Blower resistors connector (Terminal C) should be
battery voltage. If not, replace blower switch.
²Blower resistors connector (Terminal A) should be
battery voltage. If not, replace blower switch.
²Blower resistors connector (Terminal B) should be
battery voltage. If not, replace blower resistor.
AIR CONDITIONING SYSTEMÐXJ VEHICLES
DESCRIPTION
The A/C Compressor Clutch is belt-driven by the
engine. A clutch, operated by a solenoid, automati-
cally turns the compressor on and off to control evap-
orator icing.
The A/C Compressor Clutch operation is controlled
by several components: the A/C Low-Pressure
Switch, Thermostat Switch, Fuel Pump Relay, A/C
Clutch Relay and the Engine Controller.The A/C low pressure switch opens when there is
not enough refrigerant in the system. When this hap-
pens, voltage is no longer present at the Engine Con-
troller. The Engine Controller will turn off the A/C
clutch relay. With the proper refrigerant level in the
system, the low pressure switch remains closed.
When the evaporator temperature is low enough to
ice the cooling coils, the thermostat switch opens.
The Engine Controller will turn off the A/C clutch.
The thermostat switch closes when the temperature
rises. The Engine Controller will then turn the A/C
clutch relay on again.
DIAGNOSIS
Refer to the Group 8W, Wiring Diagrams for com-
plete system schematic.
With engine running, Engine Controller may delay
A/C clutch up to 30 seconds.
1. A/C COMPRESSOR CLUTCH INOPERA-
TIVE
Clutch connector disconnected.
²Jumper fused test lead, battery to clutch connec-
tor, clutch should operate. If not, replace compressor
clutch assembly.
2. A/C LOW PRESSURE SWITCH
Ignition in RUN, A/C controls in MAX or NORM.
²Low pressure switch connector (Terminal A)
should be battery voltage. If not, repair open to select
switch.
²Low pressure switch connector (Terminal C)
should be battery voltage. If not, check switch resis-
tance and check freon pressure.
3. A/C CLUTCH RELAY
Engine RUNNING, A/C controls in MAX or
NORM.
²Relay connector Pin 4 to ground should be battery
voltage. If not, check fuse F6 in Power Distribution
Center.
²Ground A/C clutch relay (Terminal 5) should have
A/C compressor clutch engagement. If not, check En-
gine Controller Terminals 27, 28 and 34.
HEATING SYSTEMÐYJ VEHICLES
DESCRIPTION
The blower motor circuit begins at a 25 amp fuse
that receives its battery feed from the ignition
switch. From the fuse the circuit extends to a micro-
switch mounted on the heater control.
The micro-switch is normally closed is operated by
a cam on the heater control lever. In all heater con-
trol lever positions, except OFF and VENT, the
blower motor electrical circuit is complete. In the
OFF and VENT positions the cam depresses the mi-
cro-switch lever opening the electrical circuit to the
blower motor.
24 - 14 HEATING AND AIR CONDITIONINGJ

COMPRESSOR OVERHAUL
INDEX
page page
Compressor............................. 17
Compressor Isolation...................... 17
Description............................. 17Magnetic Clutch......................... 18
Purging Compressor of Air................. 17
DESCRIPTION
The A/C system uses a Sanden compressor. This
compressor is a 7 piston design. Designated the SD-
709, the compressor is mounted on the front right
side of the engine and is driven by a serpentine belt.
System lubrication is provided by 135cc615cc (4.6
cu. in.60.5 cu. in.) of 500 viscosity refrigerant oil.
The clutch used on the compressor consists of 3 ba-
sic components: the pulley, front plate and the field
coil. The pulley and field coil are attached to the
front head of the compressor with tapered snap rings.
The hub is keyed to the compressor shaft and is re-
tained on the shaft with a self-locking nut. Special
service tools are required to remove and install the
clutch plate on the compressor shaft.
COMPRESSOR ISOLATION
It is not necessary to discharge the system for com-
pressor removal. The compressor can be isolated from
the remainder of the system and eliminate the need
for recharging when performing compressor service.
(1) Connect pressure gauge and manifold.
(2) Close both gauge hand valves.
(3) Mid-position both service valves.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A DI-
RECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(4) Start the engine and operate the air condition-
ing system.
(5) Turn the suction service valve slowly clockwise
toward the front seated position.
(6) When pressure drops to zero, stop the engine
and compressor and quickly finish front-seating the
suction service valve.
(7) Front-seat the discharge service valve.
(8) Loosen the oil level check plug slowly to re-
lease any internal pressure in the compressor.
The compressor is now isolated from the remainder
of the system.
The service valves can be removed from the com-
pressor.
PURGING COMPRESSOR OF AIR
The compressor must be purged of air whenever it
has been isolated for an oil level check or other ser-
vice procedures without discharging the entire sys-
tem.
(1) Cap the service gauge ports on both of the ser-
vice valves.
(2) Back-seat the suction service valve to allow the
system refrigerant to enter the compressor.
(3) Place the discharge service valve in the mid-po-
sition or cracked-position.
(4) Loosen the discharge service valve gauge port
cap to permit the refrigerant to force any air out of
the compressor.
(5) Back-seat the discharge service valve and
tighten the gauge port cap.
(6) The compressor is now ready for service.
COMPRESSOR
REMOVAL
(1) Isolate the compressor.
(2) Disconnect negative cable from battery.
(3) Disconnect the clutch lead wire.
(4) Remove the discharge and inlet (suction) ser-
vice valves from the compressor. Plug or tape all the
openings.
(5) Remove the serpentine drive belt (refer to
Group 7, Cooling System for the proper procedure).
(6) Remove the bolts and lift the compressor from
the mounting bracket (Figs. 1 and 2).
INSTALLATION
If a replacement compressor is being installed;
check the oil level. Add or subtract oil as neces-
sary and install the magnetic clutch on the com-
pressor.
(1) If the mounting bracket was removed, install
the bracket to the block. Tighten the mounting bolts
to 27 NIm (20 ft. lbs.) torque.
(2) Install the compressor on the mounting
bracket. Tighten the bolts to 27 NIm (20 ft. lbs.)
torque.
(3) Install the serpentine drive belt (refer to Group
7, Cooling System for the proper procedure).
(4) Tighten the serpentine drive belt to the speci-
fied tension.
²New belt tensionÐ800-900 N (180-200 lb-f).
JHEATING AND AIR CONDITIONING 24 - 17

CLIMATE CONTROL SYSTEMÐXJ VEHICLES
INDEX
page page
A/C Recirculating Air Door Vacuum Motor
Replacement.......................... 31
Blower Motor Resistors Replacement......... 35
Blower Motor/Fan Replacement.............. 26
CondenserÐ4.0L Engines.................. 32
Condenser/Receiver DrierÐ2.5L Engines....... 31
Defroster Duct Replacement................ 29
Description............................. 22
Evaporator Coil.......................... 34
Evaporator/Blower Housing................. 33Expansion (H) Valve...................... 35
Heater and A/C Control Panel Replacement.... 26
Heater Control Cable Replacement........... 30
Heater Core............................ 28
Heater Core Housing Replacement........... 29
Heater/Defroster/Instrument Panel Outlet Door
Vacuum Motor Replacement............... 30
Receiver DrierÐ4.0L Engines............... 32
Temperature Control Thermostat............. 35
DESCRIPTION
The Climate Control System combines air condi-
tioning, heating and ventilating capabilities for vehi-
cles equipped with air conditioning. Vehicles without
air conditioning perform heating and ventilating
functions without the air conditioning evaporator.
Both systems consist basically of 2 parts:
²Blower and Air Inlet Assembly
²Heater Core and Air Distribution Assembly
These assemblies, initially installed as a single
unit, may be removed separately from under the in-
strument panel as required for service.
HEATER SYSTEM
The heater system is a blend air type. Outside air
is heated and then blended in varying amounts with
cooler outside air to obtain the desired discharge
temperature. A heater coolant valve provides full
flow to the heater core for all heating modes. The
heater coolant valve remains closed for the ventila-
tion mode, allowing discharge air to approach the
outside ambient air temperature.
AIR CONDITIONING SYSTEM
The air conditioning system has an evaporator to
cool and dehumidify the incoming outside air prior to
blending with the heated air. The evaporator is in
operation during the A/C mode and also in the de-
frost mode for defogging purposes. The evaporator is
not in operation at ambient temperatures below ap-
proximately -1ÉC (30ÉF). To maintain minimum evap-
orator temperature, a fixed thermostat setting switch
cycles the compressor clutch. The blower is operatingthe heater or air conditioning systems, except the
OFF mode. In this mode (OFF) the blower and the
outside air are shut off.
The cooling unit is mounted on the dash panel and
the cooled air is discharged from the instrument
panel registers. The registers are adjusted to provide
general or localized cooling.
SIGHT GLASS
The sight glass is located on top of the receiver/
drier. The sight glass provides a visual check of the
system refrigerant level. A continuous stream of bub-
bles will appear in the sight glass when the system
charge is low. Bubbles will not appear when the sys-
tem is fully charged.
LOW PRESSURE SWITCH
The low pressure switch disengages the magnetic
clutch if the pressure in the system drops below 193
kPa (28 psi). This will occur with a loss in refriger-
ant or with cold ambient temperature.
HEATER VALVE
The heater valve regulates coolant flow to the
heater core. It requires vacuum to shut off flow to
the heater core.
These vehicles are equipped with a bypass-type
heater water valve. When the heater valve is closed,
coolant flow to the heater core is bypassed back to
the engine. When the heater valve is open, coolant is
directed through the heater core and back to the en-
gine.
24 - 22 HEATING AND AIR CONDITIONINGJ

(4) Connect the heater hoses to the heater core.
(5) Fill the cooling system.
HEATER CORE HOUSING REPLACEMENT
(1) Remove the evaporator/blower housing.
(2) Remove the heater core.
(3) Remove the defroster duct.
(4) Disconnect the vacuum hoses from the heater
core housing vacuum motors.
(5) Remove the heater housing retaining nuts in
the engine compartment. Remove the heater core
housing.
(6) Transfer the vacuum motors, etc. to the re-
placement housing.
To install the heater core housing, reverse the re-
moval procedure.
DEFROSTER DUCT REPLACEMENT
REMOVAL
(1) Disconnect negative cable from battery.
(2) If equipped with center console remove the con-
sole as follows:
(a) MANUAL TRANSMISSIONÐRemove shift
knob, boot and bezel.
(b) AUTOMATIC TRANSMISSIONÐRemove
shift handle by pulling up. Remove the shift bezel.
(c) POWER MIRRORSÐPry mirror switch out of
console cover (Fig. 13). Disconnect switch connector
(Fig. 14).
(d) Remove console cover screws (Fig. 14).
(e) Remove console cover from base (Fig. 15).
(f) Remove console base (Fig. 15).
(3) Remove the lower instrument panel.
(4) Remove the left kick panel.
(5) Remove the instrument panel retaining bolt.
(6) Remove the instrument panel retaining bolts
located at the steering column.
(7) Remove the right and left A-pillar trim.(8) Remove the defroster bezel attaching screws
and bezel (Fig. 16).
Fig. 13 Power Mirror Switch
Fig. 14 Console Cover Screws and Power Mirror
Switch Connector
Fig. 15 Console Cover and Base
JHEATING AND AIR CONDITIONING 24 - 29

INSTALLATION
(1) Remove the plugs from the receiver/drier open-
ings. Install receiver/drier into the condenser.
(2) Install the condenser to the radiator. Tighten
the retaining bolts.
(3) Install the radiator and condenser as an assem-
bly (refer to Group 7, Cooling System for the proper
procedure).
(4) Plug the harness into the low pressure switch
(Fig. 21).
(5) Connect the A/C hoses to the condenser.
(6) Connect the transmission cooler lines (if
equipped with automatic transmission).
(7) Connect the fan shroud and the radiator hoses.
(8) Add 30 ml (1 fluid oz.) of refrigerant oil to the
system if the condenser was replaced.
(9) Fill the cooling system.
(10) Charge the A/C system.
CONDENSERÐ4.0L ENGINES
REMOVAL
(1) Disconnect the fan shroud and electric fan from
the radiator.
(2) Remove the upper crossmember and bracket.
(3) Evacuate the A/C system, disconnect the A/C
hoses from the condenser and plug the openings.
(4) Remove the attaching hardware and brackets
securing the condenser to the radiator.
(5) Remove the condenser.
INSPECTION
When servicing a condenser for a leak at the bot-
tom, inspect the lower crossmember for an ID tag.
This tag may rub against the condenser. If the con-dition exists, remove the tag prior to installing a new
condenser.
INSTALLATION
(1) Install the condenser.
(2) Remove the plugs from the openings. Connect
the A/C hoses to the condenser.
(3) Install the upper crossmember and bracket.
(4) Connect the fan shroud and electric fan to the
radiator.
(5) Add 30 ml (1 fluid oz.) of refrigerant oil to the
A/C system if the condenser was replaced.
(6) Charge the A/C system.
RECEIVER DRIERÐ4.0L ENGINES
REMOVAL
(1) Evacuate the A/C system, disconnect the A/C
hoses from the receiver dryer and plug the openings
(Fig. 22).
(2) Unplug the harness from the low pressure
switch.
(3) Remove the nut attaching the receiver dryer to
the side sill weld stud.
(4) Remove the receiver dryer.
INSTALLATION
(1) Install the receiver dryer.
(2) Install and tighten the nut attaching the re-
ceiver dryer to the side sill weld stud.
(3) Plug the harness to the low pressure switch.
(4) Remove the plugs the openings. Connect the
A/C hoses to the receiver dryer.
(5) Charge the A/C system.
Fig. 21 Condenser Receiver DrierÐ2.5L Engine
Fig. 22 Receiver DryerÐ4.0L Engine
24 - 32 HEATING AND AIR CONDITIONINGJ

CLIMATE CONTROL SYSTEMÐYJ VEHICLES
INDEX
page page
A/C Blower Motor........................ 43
A/C Condenser.......................... 42
A/C Control Panel........................ 41
Blower Motor (Heating).................... 40
Blower Motor/Air Door Motor Switch Replacement . 39
Defroster Nozzle and Duct................. 40
Description (Air Conditioning)................ 41
Description (Heating)...................... 37
Evaporator and Housing................... 42
Expansion (H) Valve...................... 43Fresh Air Door Vacuum Motor............... 41
Fresh Air Intake Duct..................... 41
Fresh Air Ventilation...................... 39
Heater Control Panel Replacement........... 39
Heater Core and Housing.................. 40
Heater/Defroster Operation................. 37
Receiver-Drier Replacement................ 42
Sight Glass............................. 41
Vent Door Control Cables.................. 39
DESCRIPTION (HEATING)
A blend-air heating system is used in YJ vehicles.
The blend-air system provides a constant flow of en-
gine coolant through the heater core.
The temperature of heated air entering the passen-
ger compartment is controlled by regulating the
quantity of air flow through the heater core. This is
accomplished by blending a controlled amount of un-
heated air from outside the vehicle with heated air
from the heater core.
HEATER/DEFROSTER OPERATION
The heater core is connected to the engine cooling
system. It operates on the circulation of heated en-
gine coolant through the core and a supply of fresh
air drawn in through the intake grille on the cowl.
Engine coolant flows through the heater core at all
times.
The heater controls are on the heater control panel
(Fig. 1).
The air control lever (Fig. 1) operates a door in the
fresh air intake duct. The door controls the amount
of fresh air flow into the heater housing and core.
When the lever is in the OFF position, the intake
door is closed preventing air flow into the housing.The temperature control lever (Fig. 1) determines
air flow through the heater core. The lever operates
the heater housing blend-air door which controls air
flow through the core.
The blower motor is operated by the control switch
(Fig. 1). The switch provides 3 blower speeds for in-
creased air flow in heat or defrost mode.
HEATING
Maximum air flow and heater output occurs when
the air control lever is in HEAT position and the
temperature control lever is in WARM position. The
blend-air door is closed and all intake air is directed
through the heater core in this operating mode (Fig.
2).
Temperature regulation of the heated air is deter-
mined by position of the temperature control lever.
Moving the control lever from WARM to an in-be-
tween position, opens the blend-air door in the heater
housing. As the door opens, unheated outside air is
drawn into the system and blended with heated air
from the core.
DEFROSTING
The heater housing contains a defroster door to di-
vert heated air to the defroster duct and windshield
outlets (Fig. 2). Defrost air flow is controlled by the
air control lever.
For defroster operation, the air control lever must
be moved to the defrost detent. The detent is identi-
fied by the defrost symbol on the control panel. In
this position, the defroster door in the heater housing
diverts all heated air (from the core) to the defroster
duct windshield outlets.
If the air control lever is moved to any position be-
tween the heat and defrost detents, the defroster door
does not close completely. In this mode, the door re-
mains partially open causing heated air to be divided
equally between the heat and defrost outlets.
Fig. 1 Heater Control Panel
JHEATING AND AIR CONDITIONING 24 - 37

HEATER CORE AND HOUSING
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Disconnect the vent door cables.
(4) Disconnect the blower motor wire.
(5) Disconnect the defroster duct.
(6) Remove the nuts that attach the heater hous-
ing studs to the engine compartment side of the dash
panel.
(7) Remove the heater housing assembly by tilting
it downward, to disengage it from the defroster duct.
Pull it rearward and out from under the instrument
panel.
(8) Remove the heater hosing cover from the hous-
ing.
(9) Remove the heater core from the housing.
INSTALLATION
(1) Install the heater core in the housing and in-
stall the cover on the housing.
(2) Position the heater housing on the dash panel.
Be sure the housing studs all extend through the
dash panel.
(3) Install the seals on the heater core outlet and
inlet tubes and over the blower motor housing.
(4) Install the attaching nuts on the housing studs.
CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(5) Connect the defroster duct to the housing.
(6) Connect the blower motor wire.
(7) Connect the vent door control cables.
(8) Connect the heater hoses.
(9) Fill and bleed the cooling system.
(10) Check system operation.
BLOWER MOTOR (HEATING)
REMOVAL
(1) Remove the heater housing.
(2) Remove the blower motor-to-heater housing at-
taching screws/nuts.
(3) Remove the blower motor from the housing.
INSTALLATION
(1) Position the blower motor into the housing.
(2) Install and tighten the blower motor-to-heater
housing attaching screws/nuts.
(3) Install the heater housing.
(4) Check blower motor and heater operation.
DEFROSTER NOZZLE AND DUCT
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Remove the nuts attaching the heater housing
studs to the engine compartment side of the dash
panel.
(4) Disconnect the speedometer cable.
(5) Remove the glove box.
(6) Tilt the heater housing back and pull it rear-
ward and out from under the instrument panel.
(7) Disconnect the vent control cables.
(8) Remove the fresh air intake grille from the
cowl.
(9) Remove the fresh air intake duct.
(10) Lower the windshield.
(11) Remove the defroster nozzle attaching screws
and remove the nozzle and duct.
INSTALLATION
(1) Install the defroster nozzle and duct.
(2) Raise and secure the windshield.
(3) Install the fresh air intake duct.
(4) Install the fresh air intake grille on the cowl.
(5) Install the vent cables.
(6) Position the heater housing on the dash panel.
Be sure all the housing studs extend through the
dash panel.
(7) Install the seals on the blower motor and the
heater core inlet and outlet tubes.
(8) Install the attaching nuts on the housing studs.
CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(9) Install the glove box.
(10) Connect the speedometer cable.
(11) Connect the heater hoses.
24 - 40 HEATING AND AIR CONDITIONINGJ

(12) Fill and bleed the cooling system.
FRESH AIR DOOR VACUUM MOTOR
REMOVAL
(1) Remove the glove box and assist handle.
(2) Disconnect the vacuum hose from the motor.
(3) Remove the motor lever retaining clip.
(4) Remove the motor attaching nuts and remove
the motor from the fresh air duct.
INSTALLATION
(1) Position the motor on the fresh air duct and in-
stall the motor attaching nuts.
(2) Align the motor lever with the air door lever
and install the lever retaining clip.
(3) Connect the vacuum hose to the motor.
(4) Install the glove box and assist handle.
FRESH AIR INTAKE DUCT
REMOVAL
WARNING: HOT ENGINE COOLANT CAN CAUSE
SEVERE BURNS. DO NOT OPEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. ALLOW THE COOLANT
TO DECREASE TO ROOM TEMPERATURE BEFORE
STARTING REPAIR OPERATIONS.
(1) Drain approximately 1.9 liters (2 qts) of coolant
from the radiator. Drain the coolant into a clean con-
tainer.
(2) Disconnect the heater hoses.
(3) Remove the nuts attaching the heater housing
studs to the dash panel from inside the engine com-
partment.
(4) Disconnect the speedometer cable.
(5) Remove the glove box and assist handle.
(6) Tilt the heater housing back and pull it rear-
ward and out from under the instrument panel.
(7) Disconnect the vent cables.
(8) Remove the fresh air intake grille from the
cowl.
(9) Remove the fresh air intake duct.
INSTALLATION
(1) Install the fresh air intake duct.
(2) Install the defroster nozzle and duct.
(3) Raise and secure the windshield.
(4) Install the fresh air grille on the cowl.
(5) Install the vent cables.
(6) Position the heater housing on the dash panel.
Be sure all the housing studs extend through the
dash panel.
(7) Install the seals on the blower motor and
heater core inlet and outlet tubes.
(8) Install the attaching nuts on the heater hous-
ing studs.CAUTION: DO NOT over tighten the attaching nuts.
The housing could become distorted causing air
leaks and improper heater door operation. Tighten
the nuts alternately and evenly until 2 stud threads
are visible beyond each nut.
(9) Install the glove box and assist handle.
(10) Connect the speedometer cable.
(11) Connect the heater hoses.
(12) Fill and bleed the cooling system.
DESCRIPTION (AIR CONDITIONING)
The evaporator, blower fan and motor, thermostat,
expansion valve, capillary tube, air outlets and sys-
tem controls are located in the evaporator housing.
The evaporator housing is mounted under the instru-
ment panel. The compressor, condenser, receiver-
dryer and refrigerant lines are located in the engine
compartment.
A rotary-type compressor with magnetic clutch op-
erated drive pulley is used for all vehicles equipped
with air conditioning.
SIGHT GLASS
A sight glass is located on the top of the receiver-
drier (Fig. 6). The sight glass provides a visual check
of system refrigerant level. A continuous stream of
bubbles will appear in the sight glass when system
charge is low. Bubbles will not appear when the sys-
tem is fully charged.
A/C CONTROL PANEL
FAN SWITCH
The fan switch may be serviced by removing the
access plate located on the lower evaporator core
housing.
TEMPERATURE CONTROL THERMOSTAT
REMOVAL
(1) Lower the evaporator housing.
(2) Remove the attaching screws holding the top
and bottom housings together.
(3) Separate the housings.
(4) Remove the thermostat.
Fig. 6 Sight Glass (Typical)
JHEATING AND AIR CONDITIONING 24 - 41

INSTALLATION
(1) When installing a replacement temperature
control thermostat, insert the capillary tube into the
evaporator coil a minimum of 50 mm (2 inch) (Fig.
7).
CAUTION: Handle the tube with care to avoid bends
or kinks that could cause the thermostat to mal-
function.
(2) Assemble the housing and install the attaching
screws. DO NOT over tighten the attaching screws.
(3) Install the evaporator housing.
A/C CONDENSER
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAIN COCK WHEN THE COOLING SYSTEM IS
HOT AND PRESSURIZED. HOT COOLANT CAN
CAUSE SERIOUS BURNS.
(1) Discharge the system slowly to prevent loss of
compressor oil.
(2) Drain the radiator. Drain the coolant into a
clean container.
(3) Remove the fan shroud and radiator.
(4) Disconnect the pressure pipe fitting from the
condenser.
(5) Remove the condenser attaching screws and tilt
the bottom of the condenser toward the engine.Plug
all the condenser openings to prevent entry of
dirt or moisture.
(6) Working from under the vehicle, disconnect the
receiver-drier to-evaporator hose fitting from the re-
ceiver-drier.
(7) Remove the condenser and receiver-drier as an
assembly.
(8) Remove the receiver-drier from the condenser,
if necessary.
INSTALLATION
(1) If the condenser is replaced, add 30 ml (1 fluid
oz.) of refrigerant oil to the system.(2) Attach the receiver-drier to the condenser.
(3) Place the condenser in position and connect the
hose fitting to the receiver-drier.
(4) Install the condenser attaching screws.
(5) Connect the condenser pressure pipe fitting.
(6) Install the radiator and fan shroud.
(7) Fill the cooling system.
(8) Evacuate, charge and leak test the air condi-
tioning system.
RECEIVER-DRIER REPLACEMENT
REMOVAL
(1) Discharge the system slowly to prevent loss of
compressor oil.
(2) Disconnect the evaporator and condenser hose
fittings from the receiver-drier.
(3) Remove the receiver-drier attaching screws. Re-
move the receiver-drier.
INSTALLATION
(1) Position the receiver-drier in place. Install and
tighten the receiver-drier attaching screws.
(2) Connect the evaporator and condenser hose fit-
tings to the receiver-drier.
(3) Charge the system.
(4) Preform the leak test on the system.
EVAPORATOR AND HOUSING
REMOVAL
(1) Discharge the system.Discharge the system
slowly to prevent loss of compressor oil.
(2) Disconnect the inlet (suction) hose.
(3) Disconnect the receiver-drier-to-evaporator
hoses.
(4) Remove the hose clamps and dash grommet re-
taining screws.
(5) Remove the evaporator housing-to-instrument
panel attaching screws and the housing mounting
bracket screw (Fig. 8).
Fig. 7 Temperature Control Thermostat
Fig. 8 Evaporator Housing
24 - 42 HEATING AND AIR CONDITIONINGJ

AIR CONDITIONING
CONTENTS
page page
AIR CONDITIONING EQUIPMENT........... 4
AIR CONDITIONING PERFORMANCE TESTS . . 5
GENERAL INFORMATION.................. 1
REFRIGERANT LEAK TESTING, DISCHARGING,
EVACUATING AND CHARGING............ 8REFRIGERANT OIL....................... 9
SERVICE PRECAUTIONS.................. 3
WARNINGS AND CAUTIONS FOR R134A
SYSTEM.............................. 3
GENERAL INFORMATION
A/C COMPONENTS
COMPRESSORÐThe SD-709 Compressor is used
on all models. The compressor compresses the low-
pressure refrigerant vapor from the evaporator into a
high pressure, high temperature vapor. The compres-
sor is serviced as an assembly only.
CLUTCH PULLEY AND COILÐThey are
mounted on the compressor and providing a way to
drive the compressor. The compressor clutch and coil
are the only serviced parts on the SD-709 compres-
sor. When the compressor is not in operation, the
pulley free wheels on the clutch hub bearing. When
the coil is energized the clutch plate is magnetically
engaged with the pulley and turns the compressor
shaft.
CONDENSERÐThe condenser is located in front
of the engine radiator. Its function is to cool the hot
high pressure refrigerant gas. This causes it to con-
dense into high pressure liquid refrigerant.
FILTER-DRIERÐThe drier is used to remove con-
taminates and traces of moisture from the refriger-
ant system.
SIGHT-GLASSÐThe sight glass is located on top
of the filter drier. It is used as a diagnostic tool to ob-
serve refrigerant flow.
LOW-PRESSURE HIGH-PRESSURE CUT-OFF
SWITCHÐThe switch is located on the filter drier
and is wired in series with compressor clutch. When
the pressure drops down to 193 kPa (28 psi) the
switch interrupts the power to the compressor clutch.
When the pressure increases above 3100 to 3375 kPa
(450 to 490 psi) the switch interrupts the power to
the compressor clutch.
HIGH PRESSURE RELIEF VALVEÐThe valve
is located on the filter drier. The valve is used to pre-
vent excessive pressure up build of 3445 to 4135
kPag (500 to 600 psi) and above. This will prevent
damage to the compressor and other system compo-
nents.EXPANSION VALVEÐThe expansion valve is lo-
cated in the engine compartment on XJ vehicles. On
YJ vehicles it is located behind the A/C housing. Its
function is to meter refrigerant into the evaporator in
accordance with cooling requirements.
EVAPORATOR COILÐThe coil is located in the
A/C housing. Its function is to remove heat and de-
humidify the air before it enters the vehicle.
FIN SENSING CYCLING CLUTCH SWITCHÐ
The switch is attached to the evaporator coil. This
switch prevents condensate water on the evaporator
coil from freezing. It does this by cycling the com-
pressor clutch on and off. This switch is used onXJ
only
THERMOSTATÐThe thermostat is located in the
evaporator housing. Its function is to cycle the com-
pressor clutch to control temperature. The thermo-
stat is used on theYJonly.
REFRIGERANT LINESÐThe lines are used to
carry the refrigerant between the various system
components.
SERVICE PORTSÐThe high pressure service
port is located on the discharge line near the com-
pressor. The low pressure service port is located on
the suction line near the compressor. The compressor
no longer uses service valves.
After servicing the refrigerant system, always in-
stall service port caps.
REFRIGERANT
The vehicles use a new type of refrigerant called
R-134a. It is a non-toxic, non-flammable, clear color-
less liquified gas.
R-134a refrigerant is not compatible with R-12 re-
frigerant in an air conditioning system. A small
amount of R-12 in a R-134a system will cause com-
pressor failure, refrigerant oil sludge or poor A/C per-
formance.
JAIR CONDITIONING1