ac heater system manual.pdf

A/C-HEATER SYSTEM - MANUAL

1988 Jeep Cherokee

1988 Manual A/C-Heater Systems

JEEP

* PLEASE READ THIS FIRST *

CAUTION: When discharging air conditioning system, use only approved

refrigerant recovery/recycling equipment. Make every attempt

to avoid discharging refrigerant into the atmosphere.

DESCRIPTION

On Cherokee, Comanche and Wagoneer, the Climate Control

System is an integral assembly combining air conditioning, heating and

ventilating capabilities for models with air conditioning. The A/C

registers are built into instrument panel.

On Wrangler models, a dual flow unit with the capability of

recirculating air or drawing air from outside is used. It incorporates

under-dash registers and uses a blend-air type system.

The A/C components include a compressor, condenser, receiver-

drier, a sight glass (in the receiver-to-evaporator line) and

evaporator housing. Evaporator housing contains evaporator core,

expansion valve, thermostat, wiring and drain tube. Blower motor and

fan are located in blower housing, which is attached to evaporator

housing.

Vents provided in evaporator housing are adjustable to direct

air to different positions in vehicle’s interior. System controls

include fan and temperature control knobs built into lower evaporator

housing assembly or temperature and mode levers on control panel

integrated with instrument panel.

OPERATION

A/C SYSTEM CONTROLS

Temperature & Fan Control Knobs

(Wrangler)

The right rotary control knob allows selection of desired

temperature. Knob has "OFF" "1", "2" and "3" positions for different

levels of cooling. The left rotary fan switch (knob) controls blower

motor speed. Knob has "OFF", "LOW", "MED" and "HI" positions. Fan will

operate unless mode control lever is in "OFF" position.

The A/C fan switch is a 3-speed unit used in conjunction with

a blower motor resistor. Fan switch controls low, medium and high

speed operation. Switch may be serviced by removing access plate

located on lower evaporator core housing, below control panel.

The A/C temperature control switch has a thermostat unit

built-in. Cooling adjustment is done by turning knob in a clockwise

rotation. For fast, efficient system operation in hot weather, vehicle

should be purged of hot air by driving about 2-3 city blocks with at

least one window open. During this time, temperature control knob

should be rotated clockwise to "MAX" position and fan control knob

placed in "HI" position. This allows evaporator to pre-cool and avoid

typical first blast of warm air.

Temperature Control Panel

(Cherokee, Comanche & Wagoneer)

The upper temperature control (mode) lever includes "MAX",

"NORM", "BI-LEVEL", "VENT", "HEAT" and "OFF" positions. At the far end

of the scale, a symbol for defroster indicates defrost position. In

"BI-LEVEL" position, a mixture of floor heat and defroster air is

obtained.

The lower temperature control lever operates blend-air door

in heater core housing. At full right position, all air is directed

through heater core, providing maximum heat flow. At full left

position, all air is directed around heater core providing fresh air.

Control can be set in any intermediate position to provide a blend of

heated and unheated air. Heater must be in heat or defrost mode before

any air can enter vehicle.

TROUBLE SHOOTING

See JEEP TROUBLE SHOOTING at the end of this article.

REMOVAL & INSTALLATION

CONDENSER

Removal (Cherokee, Comanche & Wagoneer) NOTE: On these

models, condenser and receiver-drier are replaced

as a unit.

1) Drain radiator. Disconnect fan shroud and radiator hoses.

Disconnect automatic transmission cooler lines (if equipped).

Discharge A/C system using approved refrigerant recovery/recycling

equipment.

2) Disconnect A/C hoses from condenser. Unplug low pressure

switch. Remove radiator and condenser as an assembly. Detach condenser

retaining bolts. Separate condenser from radiator. Remove receiver-

drier from condenser.

NOTE: Plug receiver-drier openings whenever unit is removed from

condenser. Add 1 oz. of refrigerant oil (AMC No. 8132400) to

system when replacing condenser.

Installation

To install, reverse removal procedure. Fill radiator.

Evacuate, leak test, recharge and check A/C system operation.

Removal (Wrangler)

1) Discharge system (slowly to prevent loss of compressor

oil) using approved refrigerant recovery/recycling equipment. Drain

coolant. Remove fan shroud and radiator. Disconnect pressure line at

condenser. Remove condenser mounting screws. Tilt bottom of condenser

toward engine.

2) From underside of vehicle, disconnect hose attaching

receiver-drier to evaporator. Plug all openings to prevent entry of

dirt or moisture. Remove receiver-drier and condenser assembly. Remove

receiver-drier from condenser.

Installation

To install, reverse removal procedure. Fill radiator.

Evacuate, leak test, recharge and check A/C system operation.

RECEIVER-DRIER

NOTE: On Cherokee, Comanche and Wagoneer, receiver-drier is

removed with condenser and radiator as an assembly.

Removal (Wrangler)

Discharge system (slowly to prevent loss of compressor oil)

using approved refrigerant recovery/recycling equipment. Disconnect

evaporator and condenser lines from receiver-drier. Detach mounting

screws from receiver-drier bracket. Remove receiver-drier.

Installation

To install, reverse removal procedure. Evacuate, leak test,

recharge. Check A/C system for proper operation.

Fig. 1: Exploded View of Wrangler Evaporator Housing

Courtesy of Chrysler Motors.

EVAPORATOR-BLOWER HOUSING &

HEATER & EVAPORATOR CORES

NOTE: The following procedures are for vehicles with A/C-heater

systems only. For replacement of heater cores on vehicles

with heater systems only, see HEATER SYSTEMS, JEEP article.

Removal (Cherokee, Comanche & Wagoneer)

1) Disconnect battery ground. Discharge A/C system using

approved refrigerant recovery/recycling equipment. Disconnect A/C

hoses from expansion valve. Drain cooling system. Disconnect heater

hoses at core tubes. Disconnect blower motor wires and vent tube.

2) Remove console (if equipped). Remove lower instrument

panel. Disconnect electrical connectors at A/C relay, blower motor

resistors and A/C thermostat. Disconnect vacuum hose at vacuum motor.

Cut plastic retaining strap holding evaporator-blower housing to

heater core housing.

3) Disconnect blend-air heater control cable. Detach clip at

rear of blower housing flange and remove retaining screws. Remove

housing attaching nuts from studs on engine compartment side of dash

panel. Remove evaporator drain tube.

4) Remove right kick panel. Detach instrument panel support

bolt. Gently pull on right side of dash, then rotate housing downward

and toward rear of vehicle to disengage housing studs from dash panel.

Remove evaporator-blower housing.

5) To remove heater core, detach retaining screws. Remove

heater core by pulling straight out of housing. To remove evaporator

core, detach top housing retaining screws, then remove top of

evaporator housing.

6) Remove thermostatic switch and capillary tube. Detach 2

evaporator retaining screws and lift evaporator core from housing.

Remove expansion valve from evaporator.

Installation

1) To install components, reverse removal procedure. When

installing evaporator core, install thermostatic switch and capillary

tube before installing top of housing.

2) When installing heater core, ensure seal is properly

cemented in place to prevent it from moving when blower assembly is

installed. Evacuate, leak test, recharge and check A/C system

operation.

NOTE: The evaporator housing mounting location is similar to

Wrangler, except blower motor is mounted horizontally to

firewall.

Removal (Wrangler)

1) Discharge system using approved refrigerant

recovery/recycling equipment. Disconnect inlet line at compressor.

Disconnect hose, at quick-disconnect coupling, between receiver-drier

and evaporator. Remove hose clamps and dash grommet retaining screws.

See Fig. 2.

Fig. 2: Wrangler Evaporator Housing Mounting Screw Locations

Courtesy of Chrysler Motors.

NOTE: It is not necessary to discharge system to service blower

motor. Evaporator housing may be lowered from instrument

panel to gain access to blower motor mounting screws.

2) Remove screws attaching evaporator housing to instrument

panel and mounting bracket. Lower evaporator housing and pull hoses

and grommet through opening.

Installation

To install, reverse removal procedure. Evacuate, leak test,

recharge and check A/C system for proper operation.

EXPANSION VALVE

Removal (Cherokee, Comanche & Wagoneer)

Discharge A/C system using approved refrigerant

recovery/recycling equipment. Disconnect A/C hoses from expansion

valve. Disconnect expansion valve from evaporator core inlet and

outlet tubes. Remove expansion valve.

Installation

To install, reverse removal procedure. Evacuate, leak test,

recharge and check A/C system operation.

NOTE: The expansion valve is pre-set and should not be adjusted. A

faulty valve requires replacement.

Removal (Wrangler)

1) Discharge system using approved refrigerant

recovery/recycling equipment. Remove evaporator housing. Remove

insulation wrapped around suction line and expansion valve.

2) Mark capillary tube location on suction line. Disconnect

inlet and outlet connections, capillary tube clamp and equalizer tube.

Remove expansion valve.

Installation

1) Clean suction line to provide positive contact with

replacement expansion valve capillary tube. Connect inlet and outlet

hoses. Clamp capillary tube securely at marked position and connect

equalizer tube.

2) Wrap expansion valve and line with insulation. Install

evaporator housing assembly. Evacuate, leak test, recharge and check

A/C system operation.

TEMPERATURE CONTROL THERMOSTAT

Removal (Cherokee, Comanche & Wagoneer)

1) Disconnect battery ground. Remove console (if equipped).

Remove lower instrument panel. Disconnect electrical connection at

thermostat. See Fig. 3.

2) Remove capillary tube retaining screw. Remove thermostat

retaining screws. Remove capillary tube from tube guide hole.

Installation

1) To install, feed capillary tube through tube guide hole

until Red tape on capillary tube just enters hole in housing. Install

capillary tube retaining screw and clip.

2) Install thermostat retaining screws and attach electrical

connection. To complete installation, reverse removal procedure.

CAUTION: Handle capillary tube with care to avoid bends or kinks

which could cause thermostat to malfunction.

Removal (Wrangler)

Remove evaporator housing assembly. Remove lower cover.

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