1993 Jeep Cherokee
1993 AIR CONDITIONING & HEAT Chrysler Motors Corp. Heater Systems
Jeep; Cherokee & Wrangler
DESCRIPTION
Cherokee and Wrangler use a blend-air heater system. Temperature of air entering passenger compartment is controlled by regulating amount of airflow through heater core and then blending it with a controlled amount of cool air that by-passes the heater core.
OPERATION
CHEROKEE
Mode Control Lever
The upper control lever on the control panel operates a vacuum switch on back of control panel. Vacuum switch controls vacuum to defroster, floor and panel vacuum motors, as well as a vacuum-actuated heater coolant control valve. See Figs. 1 and 4. The heater coolant control valve closes when vacuum is applied to it.
Temperature Control Lever
The lower control lever on the control panel moves a cable that controls the position of the blend-air door in the heater case.
|
Mod» Lever Position |
Air Discharge |
Blower SpMdi |
Panel Door |
Floor Door |
Defrost Door |
Water Valve |
|
Off |
Closed |
None |
Closed |
Closed |
Closed |
Closed |
|
Venl |
Panel Registers |
4 |
Open |
Closed |
Closed |
Closed |
|
Bi-level |
Panel Registers and Floor With D»f Bleed |
4 |
Open |
Open |
Bleed |
Open 111 |
|
Heot |
Floor With Def Bleed |
4 |
Closed |
Open |
Bleed |
Open ID |
|
Defroster |
4 |
Closed |
Closed |
Open |
Open (1) |
(1) HEATER CONTROL VALVE CLOSES IN FULL COOL TEMPERATURE LEVER POSITION
Fig. 1: Heater System Operation (Cherokee) Courtesy of Chrysler Corp.
WRANGLER
NOTE: System does not use a heater coolant control valve. Coolant always flows through the heater core.
Mode Control Lever
The upper lever on the control panel moves 2 cables, one for the vent doors and one for the defrost/floor duct door. See Figs. 2 and 3. Lever also operates vacuum switch on back of control panel. The
vacuum switch allows or denies vacuum to the fresh air door vacuum motor.
Temperature Control Lever
The lower lever on the control panel moves a cable that controls the position of the blend-air door in the heater case.
Fig. 2: Exploded View Of Air Intake System (Wrangler) Courtesy of Chrysler Corp.
Fig. 3: Exploded View Of Heater Case (Wrangler) Courtesy of Chrysler Corp.
ADJUSTMENTS
CONTROL CABLES
Cherokee
Temperature control cable is attached to blend-air door lever by a retaining clip and a self-adjusting clip. When connecting cable to door lever, self-adjusting clip will adjust cable when it is snapped into position on lever.
Wrangler
Since left cable operates right cable, install and adjust
cables in correct sequence. This maintains self-adjusting mechanism.
Connect cables to control panel. Connect only right vent
door cable to vent door. Open and close right vent door one time by
sliding control panel lever. Connect left cable, and ensure both vent
doors open at same time.
TROUBLE SHOOTING
BLOWER DOES NOT RUN
Blown fuse. Loose connection or poor ground. Faulty switch, motor or resistor.
BLOWER RUNS AT ONE SPEED
Faulty switch or resistor.
BLOWER RUNS, BUT NO AIR CIRCULATION
Air inlet blocked. Fan not attached to motor shaft. Inoperative air inlet door.
HEAT OUTPUT WHEN CONTROLS ARE OFF
Blend-air door cable misadjusted. Blend-air door binding in housing.
LITTLE OR NO AIR FROM DEFROSTER OUTLETS
Defroster duct misaligned. Defroster cable incorrectly adjusted. Leaking air duct seals. Defroster duct damaged.
LITTLE OR NO AIR FROM FLOOR OUTLETS
Misadjusted heater air door cable. Obstructed heater housing or ducts. Clogged heater core fins. Leaking air duct seals.
NOT ENOUGH HEAT
Low coolant or plugged heater core. Incorrect thermostat. Incorrect adjustment of cables. Heater system air leaks. Blend-air door not in proper position.
REMOVAL & INSTALLATION
BLOWER MOTOR
Removal & Installation (Cherokee - 2.5L Engine)
Disconnect blower motor connector in engine compartment, near
blower motor. Remove blower motor screws. Remove blower motor. To install, reverse removal procedure.
Removal & Installation (Cherokee - 4.0L Engine)
Remove coolant bottle retaining strap. Move bottle aside.
Remove coolant bottle bracket. Remove anti-lock brake pump and bracket
as an assembly (if equipped). Move assembly aside.
Disconnect blower motor connector in engine compartment,
near blower motor. Remove blower motor screws. Remove blower motor. To
install, reverse removal procedure.
Removal & Installation (Wrangler)
Remove heater housing. See HEATER HOUSING. Remove blower motor screws and blower motor. To install, reverse removal procedure.
CONTROL CABLES
Removal (Cherokee)
Remove control panel. See CONTROL PANEL. Disconnect cable wire from blend-air door lever. Squeeze cable housing tabs together using needle-nose pliers to detach cable housing from slot in case. DO NOT break cable housing. Remove cable.
Installation
Connect cable wire to blend-air door lever. Snap cable housing tabs into slot in case. Route cable to control panel. Connect cable wire to control panel. Install control panel.
Removal & Installation (Wrangler)
Disconnect cables from vent doors. Disconnect cables from control panel levers. Remove cables by squeezing tabs using needle-nose pliers. Remove cable. Connect and adjust cables. See ADJUSTMENTS.
CONTROL PANEL
Removal & Installation
Disconnect negative battery cable. Remove 6 screws from
instrument panel bezel. Remove bezel (on Cherokee, bezel is snap-
fitted to instrument panel). Remove radio (if equipped).
Remove control panel screws. Pull out control panel and
disconnect vacuum hoses, wires and cables. Note locations for
installation reference. Remove control panel. To install, reverse
removal procedure.
HEATER CORE
Removal & Installation (Cherokee)
Drain cooling system. Disconnect heater hoses from heater
core tubes. Remove blower housing. Remove heater core screws. Pull
heater core out of housing.
To install, cement heater core seal in place to prevent it
from moving during installation. Insert heater core into housing. To
install remaining components, reverse removal procedure.
Removal & Installation (Wrangler)
Remove heater housing. See HEATER HOUSING. Remove cover from housing. Remove heater core from housing. To install, reverse removal procedure.
HEATER HOUSING
Removal & Installation (Cherokee)
Disconnect negative battery cable. Drain cooling system.
Disconnect blower motor connector in engine compartment, near blower
motor. Remove console (if equipped). Remove lower instrument panel.
Disconnect blower motor resistor connector. Disconnect
vacuum hose from vacuum motor. Cut plastic strap holding blower
housing to heater housing.
Disconnect control cable from blend-air door lever. Remove
control cable. Remove clip from rear of blower housing flange, and
remove housing screws. Remove right kick panel.
Remove instrument panel support bolt. To disengage blower
housing studs from firewall, gently pull out right side of instrument
panel and then rotate blower housing downward and rearward. Remove
blower housing.
Remove heater core screws. Remove heater core. Remove
defroster duct. Disconnect vacuum hoses from vacuum motors. Remove
heater housing nuts from engine compartment firewall. Remove heater
housing.
To install, reverse removal procedure. Before installing
heater core, cement core seal to core to keep it in place during
installation. After installation, fill cooling system.
Removal & Installation (Wrangler)
Disconnect negative battery cable. Drain about 2 quarts of
coolant from radiator. Disconnect heater hoses from core tubes.
Disconnect vent door cables. Disconnect blower motor connector in
engine compartment, near blower motor. Disconnect defroster duct.
Remove heater housing nuts from studs on engine
compartment firewall. Tilt heater housing downward to disengage it from defroster duct. Pull heater housing rearward and out from under instrument panel. To install, reverse removal procedure.
Fig. 4: Heater Control System Vacuum Diagram (Cherokee) Courtesy of Chrysler Corp.
WIRING DIAGRAMS
VACUUM DIAGRAM
BLOWER RESISTOR
(RIGHT SIDE,
UPPER HEATER
HOUSING)
93G28932
Fig. 5: Heater System Wiring Diagram (Cherokee)
Fig. 6: Heater System Wiring Diagram (Wrangler)
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