Fresh Air Ventilation; Heating System Diagnosis - Jeep 1987 Wrangler Workshop Manual

HEATING AND AIR CONDITIONING
HEATING SYSTEM
NOTE: if the air control lever (2) is moved to any
position between the heat and defrost detents,
the defroster door does not close completely.
In this mode, the door remains partially open
causing heated air to be divided equally be-
tween the heat and defrost outlets.
FRESH AIR VENTILATION
The fresh air ventilating system is operated by
the air control lever (2). When the lever is
moved to Vent position, outside air from the
cowl intake flows into the heater housing. In-
coming air is directed into the vehicle interior
through vent doors in the housing.
A door in the intake duct controls air flow into
the duct. The door is operated by a vacuum
motor. The motor is controlled by a vacuum
switch in the heater control panel. The vent air
doors are opened and closed by a cable and
linkage operated by the air control lever. Fresh
air intake occurs only when the lever is in the
Vent position.
HEATING SYSTEM DIAGNOSIS
Service Diagnosis
Condition Possible Cause
Correction
BLOWER MOTOR
(1)
Blown fuse
(1) Replace fuse
WILL NOT TURN
(2)
Loose connection
(2)
Inspect and tighten
AT ANY SPEED
(3)
Defective ground (3)
Clean and tighten
(4) Faulty switch (4) Replace switch
(5) Faulty motor
(5) Replace motor
(6) Faulty resistor
(6) Replace resistor
BLOWER MOTOR TURNS
(1) Faulty switch
(1) Replace switch
AT ONE SPEED ONLY
(2) Faulty resistor
(2) Replace resistor
BLOWER MOTOR TURNS
(1) Intake blocked
(1) Clean intake
BUT DOES NOT
(2)
Fan not secured to the
(2) Tighten securely
C I R C U L A T E AIR motor shaft
HEATER W I L L NOT
(1) Coolant does not reach
(1) Check and replace
HEAT
proper temperature
thermostat if necessary
(2)
Heater core blocked
(2)
Flush or replace core
internally
(2)
if necessary
(3) Heater core air-bound
(3)
Purge air from core
(4) Blend-air door not in (4) Adjust cable
proper position
HEATER W I L L NOT
(1) Control cable adjustment (1) Adjust control cable
DEFROST
incorrect
Adjust control cable
(2) Defroster hose damaged
(2) Replace defroster hose
I
SEE
I.S.
N
O
T
E
S
80587A
L-5