1994 JEEP CHEROKEE heater

The blower switch allows the driver to select 1 of 3
blower speedsÐlow, medium and high. In the high
speed position, the switch connects the motor directly
to the battery source. The remaining 2 slower speeds
are accomplished by routing the battery source
through a resistor assembly.
The resistor and switch are wired in such a way
that only a single wire is needed to operate the
blower motor at 3 different speeds.
DIAGNOSIS
Refer to Group 8W, Wiring Diagrams for complete
system schematic.
1. HEAT/OFF MICRO-SWITCH
Place selector lever in heat mode and turn ignition
switch to RUN.
²Heat/Off micro-switch connector supply side should
be battery voltage. If not, repair open from fuse
No.12.
²Heat/Off micro-switch connector output side should
be battery voltage. If not, replace Heat/Off micro-
switch.
2. BLOWER SWITCH
Turn ignition switch to RUN and place selector le-
ver in HEAT mode.
²Blower switch (terminal A) should be battery volt-
age. If not, repair open from HEAT/OFF switch con-
nector output side to blower switch.
²Blower switch (terminal D) with blower switch in
HI should be battery voltage. If not, replace blower
switch.
²Blower switch (terminal C) with blower switch in
LO should be battery voltage. If not, replace blower
switch.
²Blower switch (terminal B) with blower switch in
MED should be battery voltage. If not replace blower
switch.
3. BLOWER RESISTOR
Turn ignition switch to RUN for voltage tests and
turn ignition switch to OFF for resistance tests.
²Blower resistor (Terminal A) with blower switch in
LO should be battery voltage. If not, repair open be-
tween blower switch and blower resistor.
²Blower resistor (Terminal C) with blower switch in
MED should be battery voltage. If not, repair open
between blower switch and blower resistor.
²Blower resistor (Terminal B) with blower switch in
HI should be battery voltage. If not, repair open be-
tween blower switch and blower resistor.
²Blower resistor between Terminals A and B should
be 3.25 ohms, if not replace blower resistor.
²Blower resistor between Terminals B and C should
be 0.60 ohms. If not, replace blower resistor.
²Blower resistor between terminals A and C should
be 2.65 ohms, if not replace blower resistor.4. BLOWER MOTOR
Turn blower motor switch to HI and place selector
lever in HEAT mode. Turn ignition switch to RUN
for voltage tests or to OFF for resistance tests.
²Blower motor voltage should be battery voltage. If
not, repair open from blower switch.
²Blower motor case to clean chassis ground should
be 0 ohms. If not, repair/replace blower motor.
AIR CONDITIONING SYSTEMÐYJ VEHICLES
DESCRIPTION
The air conditioning circuit consists of 3 segments;
battery supply, blower motor and compressor clutch.
The 3 segments have a common connection point at
the blower switch.
The power supply segment of the circuit extends
from the 25 amp HTR/FAN fuse to the blower
switch. From the blower switch, battery feed is
routed to the blower motor and compressor clutch
segments of the circuit.
The blower motor segment consists of the 3 wires
from the blower switch to the motor, the motor itself
and the motor ground wire. Through the switch, the
3 wires connect the motor brushes to battery supply.
When connected to battery feed, the separate brushes
provide the 3 blower speedsÐLO, MED, and HIGH.
In all blower switch positions except OFF, the com-
pressor clutch segment of the circuit also receives
battery feed. ON and OFF cycling of the compressor
and therefore the temperature of the outlet air is
regulated by the thermostatic control. A thermal sen-
sor extends from the control to the evaporator hous-
ing. When the temperature of the evaporator drops
below the set temperature, the thermostatic control
opens the clutch circuit. The circuit remains open un-
til evaporator temperature rises above the set tem-
perature.
The compressor clutch segment of the circuit also
contains a low pressure switch. If the pressure in the
refrigerant system drops due to a leak, the circuit is
opened to prevent damage to the compressor.
The last component in the compressor clutch seg-
ment of the circuit is the clutch coil. When the coil is
connected to battery feed, its windings form an elec-
tromagnet that pulls the clutch hub against the
clutch pulley.
DIAGNOSIS
BLOWER MOTOR
Refer to Group 8W, Wiring Diagrams for complete
system schematic.
1. FUSEÐIgnition in RUN.
²Heater blower motor operates. If not, check fuse
No.12.
JHEATING AND AIR CONDITIONING 24 - 15

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

HEATER AND A/C CONTROL PANEL REPLACEMENT
(1) Disconnect negative cable from battery.
(2) Remove the instrument panel bezel attaching
screws and remove the instrument panel bezel (Fig.
1). Bezel is snap fit at locations shown.
(3) Remove the radio attaching screws (Fig. 2).
(4) Disconnect the radio electrical connector,
ground lead and antenna lead (Fig. 3).
(5) Remove the A/C-heater control panel screws
(Fig. 4).(6) Remove the electrical connectors (Fig. 5).
(7) Disconnect the vacuum hoses by releasing the
locking tabs (Fig. 6).
(8) Remove the control cable locking tab by using
a screwdriver to release the tab (Fig. 7).
(9) Remove the ring on the end of the control cable
from the arm on the bottom of the control panel (Fig.
8).
To Install the A/C-heater control panel, reverse the
removal procedures.
BLOWER MOTOR/FAN REPLACEMENT
The blower motor and fan are accessible and
may be removed from the engine compartment.
2.5L ENGINE
(1) Disconnect the blower motor wires (Fig. 9).
(2) Remove the blower motor and fan assembly
mounting screws (Fig. 10).
(3) Remove the blower motor and fan assembly.
(4) Remove the blower motor fan from the motor
shaft for access to the motor attaching nuts (Fig. 11).
Fig. 1 Instrument Bezel
Fig. 2 Radio Mounting Screws
Fig. 3 Radio Wiring Harness
Fig. 4 Control Panel Mounting Screws
24 - 26 HEATING AND AIR CONDITIONINGJ

HEATER CORE
REMOVAL
(1) Drain the radiator.
(2) Disconnect the heater hoses at the heater core
inlet and outlet tubes.
(3) Remove the evaporator/blower housing.
(4) Remove the retaining screws and remove the
heater core by pulling it straight out of the housing
(Fig. 12).
INSTALLATION
(1) Install the heater core into the housing and in-
stall the screws.
(2) Install the evaporator/blower housing.
(3) Cement the seal into place in order to keep it
from moving when the blower assembly is installed.
Fig. 9 Blower Motor Connector
Fig. 10 Blower Motor Mounting Screws
Fig. 11 Blower Fan
Fig. 12 Heater Core
24 - 28 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

(9) Remove the instrument panel retaining screws.
(10) Lower the steering column.
(11) Pull the instrument panel, approximately 3
inches, away from the dash panel.
(12) Remove the defroster duct retaining screws.
Remove the defroster duct.
(13) Disconnect the hoses.
INSTALLATION
(1) Connect the hoses.
(2) Install the defroster duct. Install the defroster
duct retaining screws.
(3) Position the instrument panel into the dash
panel.
(4) Position the steering column.
(5) Install the instrument panel retaining screws.
(6) Install the defroster bezel attaching screws and
bezel.
(7) Install the right and left A-pillar trim.
(8) Install the instrument panel retaining bolts lo-
cated at the steering column. Tighten the steering
column retaining nuts to 27 NIm (20 ft. lbs.) torque.
(9) Install and tighten the instrument panel re-
taining bolt.
(10) Install the left kick panel.
(11) Install the lower instrument panel.
(12) If equipped with center console, install the
console as follows:
(a) Install console base.
(b) Install console cover to base.
(c) Install and tighten console cover screws.
(d) POWER MIRRORSÐSnap mirror switch into
the console cover. Connect switch connector.
(e) MANUAL TRANSMISSIONÐInstall shift
knob, boot and bezel.(f) AUTOMATIC TRANSMISSIONÐInstall the
shift bezel. Install shift handle by pushing down.
(13) Connect negative cable to battery.
HEATER CONTROL CABLE REPLACEMENT
(1) Remove the heater control panel.
(2) Remove the clip and the cable self-adjusting
clip from the blend air door lever at the bottom of
the evaporator/blower housing (Fig. 17). Then re-
move the cable by squeezing the tabs with needle
nose pliers being careful not to break the housing.
To install the heater control cable, reverse the re-
moval procedure.
HEATER/DEFROSTER/INSTRUMENT PANEL OUTLET
DOOR VACUUM MOTOR REPLACEMENT
(1) 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.
(2) Remove the lower instrument panel.
(3) Disconnect the vacuum hose(s) from the vac-
uum motor.
(4) Remove the vacuum motor attaching nuts and
remove the vacuum motor from the bracket.
Fig. 16 Defroster Bezel
Fig. 17 Heater Control
24 - 30 HEATING AND AIR CONDITIONINGJ

EVAPORATOR/BLOWER HOUSING
REMOVAL
(1) Disconnect negative cable from battery.
(2) Discharge the A/C system as described in this
section and disconnect the A/C hoses from the expan-
sion valve.
(3) Disconnect the blower motor wires and the vent
tube.
(4) 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) and disconnect switch con-
nector (Fig. 14).
(d) Remove console cover screws (Fig. 14).
(e) Remove console cover from base (Fig. 15).
(f) Remove console base.
(5) Remove the lower instrument panel.
(6) Disconnect the electrical connections at the
blower motor resistors and the A/C thermostat. Dis-
connect the vacuum hose at the vacuum motor (Fig.
23).
(7) Cut the plastic retaining strap that retains the
evaporator/blower housing to the heater core housing
(Fig. 24).
(8) Disconnect and remove the heater control ca-
ble.
(9) Remove the clip at the rear of the blower hous-
ing flange and remove the retaining screws.(10) Remove the housing attaching nuts from the
studs on the engine compartment side of the dash
panel (Fig. 25). Remove the evaporator drain tube.
(11) Remove the right kick panel and then remove
the instrument panel support bolt.
(12) To disengage the housing studs from the dash
panel, gently pull out on the right side of the dash.
Then rotate the housing downward and toward the
rear of the vehicle. Remove the evaporator/blower
housing.
Fig. 23 Evaporator Housing Components
Fig. 24 Evaporator Housing
Fig. 25 Evaporator Housing Mounting
JHEATING AND AIR CONDITIONING 24 - 33

INSTALLATION
(1) Position the evaporator/blower housing into
place, being sure to line up the housings using the
provided alignment tabs (Figs. 26 and 27).
(2) Install the housing retaining screws and the
rear housing clip (Fig. 25).
CAUTION: When installing the evaporator/blower
housing, DO NOT trap wires between the housing
fresh air inlet and the dash panel (right side of
housing).
(3) Install the housing retaining nuts on the en-
gine compartment side of the dash panel (Fig. 25).(4) Connect the A/C hoses to the expansion valve
and connect the heater blower motor wires.
(5) Attach the wire connections at the blower mo-
tor resistors and the A/C thermostat (Fig. 23).
(6) Connect the vacuum hose at the vacuum motor
and attach the heater control cable.
(7) Install the instrument panel bolt and the kick
panel.
(8) Install the lower instrument panel and screws.
(9) Install the console (if equipped).
(10) Connect negative cable to battery.
(11) Evacuate and charge the A/C system as out-
lined in this section.
(12) Start the vehicle and check for proper opera-
tion at all vacuum motors.
EVAPORATOR COIL
REMOVAL
(1) Remove the evaporator/blower housing.
(2) Remove the top housing retaining screws. Re-
move the top of the evaporator housing (Fig. 28).
(3) Remove the thermostatic switch and capillary
tube after removing the top of the evaporator hous-
ing.
(4) Remove the evaporator retaining screws and
lift the evaporator out of the housing (Fig. 29).
(5) Remove the expansion valve from the evapora-
tor.
INSTALLATION
(1) Install the expansion valve into the evaporator.
(2) Position the evaporator in the housing. Install
and tighten the evaporator retaining screws (Fig.
29).
(3) Install the thermostatic switch and capillary
tube. Install the top of the evaporator housing.
(4) Position the top of the evaporator housing in
place. Install and tighten the top housing retaining
screws.
Fig. 26 Evaporator Housing Alignment Tab
Fig. 27 Evaporator Housing
Fig. 28 Top of Housing
24 - 34 HEATING AND AIR CONDITIONINGJ