Jeep Cherokee 2000, Service Manual

Page: 1467 / 1528

BLOWER MOTOR RESISTOR
DESCRIPTION
The blower motor resistor is mounted to the bot-
tom of the heater-A/C housing on the passenger side
of the vehicle under the instrument panel. It can be
accessed for service by removing the heater-A/C
housing kick cover.
OPERATION
The resistor has multiple resistor wires, each of
which reduce the current flow to the blower motor, to
change the blower motor speed. The blower motor
switch directs the ground path through the correct
resistor wire to obtain the selected speed. When the
highest blower speed is selected, the blower motor
switch connects the blower motor directly to ground,
bypassing the blower motor resistor.
The blower motor resistor cannot be repaired and,
if faulty or damaged, it must be replaced.
BLOWER MOTOR SWITCH
DESCRIPTION
The heater-only or heater-A/C blower motor is con-
trolled by a four position rotary-type blower motor
switch, mounted in the heater-A/C control panel. The
switch allows the selection of one of four blower
motor speeds, but can only be turned off by selecting
the Off position with the heater-A/C mode control
switch knob.
OPERATION
The blower motor switch directs the blower motor
ground path through the mode control switch to the
blower motor resistor, or directly to ground, as
required to achieve the selected blower motor speed.
The blower motor switch cannot be repaired and, if
faulty or damaged, the entire heater-only or heater-
A/C control unit must be replaced.
COMPRESSOR
DESCRIPTION
The air conditioning system uses a Sanden
SD7H15 seven cylinder, reciprocating wobble plate-
type compressor on all models. This compressor has a
fixed displacement of 150 cubic centimeters (9.375
cubic inches), and has both the suction and discharge
ports located on the cylinder head. A label identifying
the use of R-134a refrigerant is located on the com-
pressor.
OPERATION
The compressor is driven by the engine through an
electric clutch, drive pulley and belt arrangement.
The compressor is lubricated by refrigerant oil that is
circulated throughout the refrigerant system with the
refrigerant.
The compressor draws in low-pressure refrigerant
vapor from the evaporator through its suction port. It
then compresses the refrigerant into a high-pressure,
high-temperature refrigerant vapor, which is then
pumped to the condenser through the compressor dis-
charge port.
The compressor cannot be repaired. If faulty or
damaged, the entire compressor assembly must be
replaced. The compressor clutch, pulley and clutch
coil are available for service.
COMPRESSOR CLUTCH
DESCRIPTION
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a hub bearing and pul-
ley assembly, and a clutch plate (Fig. 2). The
electromagnetic coil unit and the hub bearing and
pulley assembly are each retained on the nose of the
compressor front housing with snap rings. The clutch
plate is keyed to the compressor shaft and secured
with a nut. These components provide the means to
engage and disengage the compressor from the
engine serpentine accessory drive belt.
OPERATION
When the clutch coil is energized, it magnetically
draws the clutch into contact with the pulley and
drives the compressor shaft. When the coil is not
energized, the pulley freewheels on the clutch hub
Fig. 2 Compressor Clutch - Typical
1 – CLUTCH PLATE
2 – SHAFT KEY
3 – PULLEY
4 – COIL
5 – CLUTCH SHIMS
6 – SNAP RING
7 – SNAP RING
XJ
HEATING AND AIR CONDITIONING 24 - 3
DESCRIPTION AND OPERATION (Continued)