Low Pressure Cycling Clutch Switch; Refrigerant System Leaks - Jeep Wrangler 1997 Manual

24- 1 8
HEATING AND AIR CONDITIONING
DIAGNOSIS AND TESTING (Continued)
RELAY TEST
The high speed blower motor relay is located near
the passenger side end of the heater-A/C housing
next to the heater-A/C wire harness connector under
the instrument panel. Remove the relay from its con-
nector to perform the following tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2 . If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75±5 ohms. If OK, go to Step
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86 .
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, see the Relay Circuit Test in this
group. If not OK, replace the faulty relay.
30
NUMBER
30
85_
86
87
87A
RELAY TERMINALS
IDENTIFICATION
COMMON FEED
COIL GROUND
COIL BATTERY
NORMALLY OPEN
NORMALLY CLOSED
TERMINAL LEGEND
85
RELAY CAVITIES
87
87A
30
High Speed Blower Motor Relay
86
J958A-2
RELAY CIRCUIT TEST
(1)
The relay common feed terminal cavity (30) is
connected to the blower motor. This terminal supplies
fused battery feed directly from a fuse in the Power Dis-
tribution Center (PDC) when the relay is energized, and
ignition switched battery feed from a fuse in the fuse-
block module through the blower motor resistor when
the relay is de-energized . There should be continuity
between this cavity and the blower motor feed circuit
cavity of the blower motor connector at all times. If
OK, go to Step 2 . If not OK, repair the open circuit
as required .
(2) The relay normally closed terminal cavity (87A) is
connected to the blower motor resistor output . When the
relay is de-energized, terminal 87A is connected to ter-
minal 30 and provides the blower motor resistor output
to the blower motor feed circuit. There should be
continuity between this cavity and the blower resis-
tor outputs circuit cavity of the blower motor resis-
tor connector at all times. If OK, go to Step 3. If not
OK, repair the open circuit as required .
TJ
(3)
The relay normally open terminal cavity (87) is
connected to a fused battery feed from the PDC .
When the relay is energized, terminal 87 is con-
nected to terminal 30 and provides full battery cur-
rent to the blower motor feed circuit. There should
be battery voltage at this cavity at all times. If OK,
go to Step 4. If not OK, repair the open circuit to the
PDC as required .
(4) The coil battery terminal cavity (86) is connected
to the high speed output contacts of the blower motor
switch . When the blower motor switch is placed in the
high speed position, fused ignition switch output is
directed to the relay electromagnetic coil to energize the
relay. There should be continuity between the cavity for
relay terminal 86 and the high blower motor relay
control circuit cavity of the blower motor switch con-
nector at all times. If OK, go to Step 5. If not OK,
repair the open circuit as required .
(5) The coil ground terminal cavity (85) is con-
nected to ground . This terminal supplies the ground
for the relay electromagnet coil . There should be con-
tinuity between the cavity for relay terminal 85 and
a good ground at all times. If not OK, repair the open
circuit as required .
LOW PRESSURE CYCLING CLUTCH SWITCH
Verify that the refrigerant system has the correct
refrigerant charge . For circuit descriptions and dia-
grams, refer to 8W-42 - Air Conditioning/Heater in
Group 8W - Wiring Diagrams .
(1) Unplug the low pressure cycling clutch switch
connector from the switch on the accumulator, and
install a jumper wire between the two connector cav-
ities.
(2) Connect a manifold gauge set to the refrigerant
system service ports.
(3) Place the heater-A/C mode control switch knob
in any A/C position and start the engine .
(4) Check the continuity between the two termi-
nals of the low pressure switch . There should be con-
tinuity with a suction pressure reading of 262 kPa
(38 psi) or above, and no continuity with a suction
pressure reading of 141 kPa (20.5 psi) or below. If
OK, test and repair the A/C switch sense circuit as
required . If not OK, replace the faulty switch .
REFRIGERANT SYSTEM LEAKS
WARNING : REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS GROUP BEFORE
LEAK TESTING THE SYSTEM .
If the air conditioning system is not cooling prop-
erly, determine if the refrigerant system is fully-
charged. See A/C Performance in this group. If the
refrigerant system is low or empty, a leak at a line,
fitting, or component seal is likely. Fittings, lines, or