Blower Inoperative; Compressor Clutch Inoperative - Jeep 1987 Wrangler Workshop Manual

DESCRIPTION
The air conditioning circuit consists of three segments—
battery feed, blower motor and compressor clutch. The
three segments have a common connection point at the
blower switch.
The power feed 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 three wires
from the blower switch to the motor, the motor itself and
the motor ground wire. Through the switch, the three
wires connect the motor brushes to battery feed. When
connected to battery feed, the separate brushes provide
the three blower speeds—LO, 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 there-
fore the temperature of the outlet air is regulated by the
thermostatic control. A thermal sensor extends from the
control to the evaporator housing. When the temperature
of the evaporator drops below the set temperature, the
thermostatic control opens the clutch circuit. The circuit
remains open until evaporator temperature rises above
the set temperature.
AIR CONDITIONING
The compressor clutch segment of the circuit also con-
tains a low pressure switch. If the pressure in the refrig-
erant system drops due to a leak, the circuit is opened to
prevent damage to the compressor.
The last component in the compressor clutch segment
of the circuit is the clutch coil. When the coil is connected
to battery feed, its windings form an electromagnet that
pulls the clutch hub against the clutch pulley.
OPERATIONAL CHECK
Turn the ignition key to the run position, set the ther-
mostat control to maximum cooling and turn the blower
switch to the LO position. When the blower motor is
switched on, a loud click will be heard as the compressor
clutch engages.
Start the engine and set the blower switch on HIGH.
After a short period of time, cold air should discharge
from the registers.
Rotate the thermostat control from maximum cool to
minimum cool and listen for the compressor clutch to
disengage. Rotate the thermostat from minimun to max-
imum several times and listen for engagement and disen-
gagement of the clutch.
3, BLOWER MOTOR: Ignition ON; blower switch position as indicated;
tests made on blower motor side off connector C109
TROUBLESHOOTING —Blower Inoperative
1. FUSE: Ignition ON
TEST
OK NOT OK
Check operation of heater
blower motor
Blower operates Check FAN/HTR fuse
Battery side of
FAN/HTR fuse
12 volts Repair open from ignition switch
A/C terminal in fuse
panel blower switch in
any position
12 volts Repair open from FAN/HTR fuse
2. BLOWER SWITCH: Ignition ON; blower switch position as indicated
TEST
OK NOT
OK
Terminal A—blower
switch in any position
12 volts Repair open from fuse panel
Terminal E—blower
switch in LO
12 volts Replace switch
Terminal D—blower
switch in MED
12 volts Replace switch
Terminal C—blower
switch in HIGH
12 volts Replace switch
TEST OK
NOT OK
A/C blower housing to
chassis ground
Zero ohms
Repair ground connection
If zero ohms, replace motor
Connector CI09 terminal
C—blower switch in LO
12 volts
Repair open from blower switch
If 12 volts, replace motor
Connector CI09 terminal
B—blower switch in MED
12 volts Repair open from blower switch
If 12 volts, replace motor
Connector CI09 terminal
A—blower switch in
HIGH
12 volts Repair open from blower switch
If 12 volts, replace motor
TROUBLESHOOTING —Compressor Clutch Inoperative
1. A/C COMPRESSOR CLUTCH
TEST OK
NOT OK
Jumper wire from battery
positive post to clutch coil
connector
Clutch engages Next step with jumper installed
Jumper wire from clutch
coil frame to clean chassis
ground
Clutch engages Repair clutch coil ground
If clutch does not engage, replace coil
2. LOW PRESSURE SWITCH: Ignition ON; A/C blower switch ON;
thermostatic control set to MAX cool
TEST
OK NOT OK
Connector terminal A 12 volts Proceed to thermostatic control tests
Jumper wire across con-
nector terminals
Clutch engages Check system refrigerant charge
If system is properly charged, replace low
pressure switch
Check system refrigerant charge
If system is properly charged, replace low
pressure switch
3. THERMOSTATIC CONTROL: Ignition ON; A/C blower switch ON;
thermostatic control set to MAX cool
TEST
OK
NOT OK
Terminal A 12 volts Repair open from blower switch
Terminal B
12 volts Replace thermostatic control
Low pressure switch ter-
minal A
12 volts Repair open from thermostatic control
Air Conditioning
31
Air Conditioning
31