Jeep XJ. Manual — part 510
nal 85 and a good ground at all times. If not OK,
repair the open circuit as required.
BLOWER MOTOR RESISTOR
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
TO
GROUP
8M
-
PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
STEERING
COLUMN,
OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the kick cover from the heater-A/C
housing and unplug the wire harness connector from
the blower motor resistor.
(3) Check for continuity between each of the
blower motor switch input terminals of the resistor
and the resistor output terminal. In each case there
should be continuity. If OK, repair the wire harness
circuits between the blower motor switch and the
blower motor resistor or blower motor relay as
required. If not OK, replace the faulty blower motor
resistor.
BLOWER MOTOR SWITCH
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS,
REFER
TO
GROUP
8M
-
PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING
WHEEL,
STEERING
COLUMN,
OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Check for battery voltage at the fuse in the
Power Distribution Center (PDC). If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse.
(2) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the heater-A/C control from the instrument
panel. Check for continuity between the ground cir-
cuit cavity of the heater-A/C control wire harness
connector and a good ground. There should be conti-
nuity. If OK, go to Step 3. If not OK, repair the open
circuit to ground as required.
(3) With the heater-A/C control wire harness con-
nector unplugged, place the heater-A/C mode control
switch knob in any position except the Off position.
Check for continuity between the ground circuit ter-
minal and each of the blower motor driver circuit ter-
minals of the heater-A/C control as you move the
blower motor switch knob to each of the four speed
positions. There should be continuity at each driver
circuit terminal in only one blower motor switch
speed position. If OK, test and repair the blower
driver circuits between the heater-A/C control con-
nector and the blower motor resistor as required. If
not OK, replace the faulty heater-A/C control unit.
COMPRESSOR
When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neu-
tral, engine speed, engine temperature, and any
other special conditions. Noises that develop during
air conditioning operation can often be misleading.
For example: What sounds like a failed front bearing
or connecting rod, may be caused by loose bolts, nuts,
mounting brackets, or a loose compressor clutch
assembly.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for a compressor
noise. Improper belt tension can cause a misleading
noise when the compressor clutch is engaged, which
may not occur when the compressor clutch is disen-
gaged. Check the serpentine drive belt condition and
tension as described in Group 7 - Cooling System
before beginning this procedure.
(1) Select a quiet area for testing. Duplicate the
complaint conditions as much as possible. Switch the
compressor on and off several times to clearly iden-
tify the compressor noise. Listen to the compressor
while the clutch is engaged and disengaged. Probe
the compressor with an engine stethoscope or a long
screwdriver with the handle held to your ear to bet-
ter localize the source of the noise.
(2) Loosen all of the compressor mounting hard-
ware and retighten. Tighten the compressor clutch
mounting nut. Be certain that the clutch coil is
mounted securely to the compressor, and that the
clutch plate and pulley are properly aligned and have
the correct air gap. See Compressor and Compressor
Clutch in the Removal and Installation section of this
group for the procedures.
(3) To duplicate a high-ambient temperature condi-
tion (high head pressure), restrict the air flow
through the condenser. Install a manifold gauge set
24 - 14
HEATING AND AIR CONDITIONING
XJ
DIAGNOSIS AND TESTING (Continued)
to be certain that the discharge pressure does not
exceed 2760 kPa (400 psi).
(4) Check the refrigerant system plumbing for
incorrect routing, rubbing or interference, which can
cause unusual noises. Also check the refrigerant lines
for kinks or sharp bends that will restrict refrigerant
flow, which can cause noises. See Suction and Dis-
charge Line in the Removal and Installation section
of this group for more information.
(5) If the noise is from opening and closing of the
high pressure relief valve, evacuate and recharge the
refrigerant system. See Refrigerant System Evacuate
and Refrigerant System Charge in the Service Proce-
dures section of this group. If the high pressure relief
valve still does not seat properly, replace the com-
pressor.
(6) If the noise is from liquid slugging on the suc-
tion line, replace the accumulator. See Accumulator
in the Removal and Installation section of this group
for the procedures. Check the refrigerant oil level
and the refrigerant system charge. See Refrigerant
Oil Level and Refrigerant System Charge in the Ser-
vice Procedures section of this group. If the liquid
slugging condition continues following accumulator
replacement, replace the compressor.
(7) If the noise continues, replace the compressor
and repeat Step 1.
COMPRESSOR CLUTCH COIL
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams. The battery must be fully-charged
before performing the following tests. Refer to Group
8A - Battery for more information.
(1) Connect an ammeter (0 to 10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0 to 20 volt scale) with clip-type leads for measuring
the voltage across the battery and the compressor
clutch coil.
(2) With the heater-A/C mode control switch in any
A/C mode, and the blower motor switch in the lowest
speed position, start the engine and run it at normal
idle.
(3) The compressor clutch coil voltage should read
within two volts of the battery voltage. If there is
voltage at the clutch coil, but the reading is not
within two volts of the battery voltage, test the
clutch coil feed circuit for excessive voltage drop and
repair as required. If there is no voltage reading at
the clutch coil, use a DRB scan tool and the proper
Diagnostic Procedures manual for testing of the com-
pressor clutch circuit. The following components
must be checked and repaired as required before you
can complete testing of the clutch coil:
• Fuses in the junction block and the Power Dis-
tribution Center (PDC)
• Heater-A/C mode control switch
• Compressor clutch relay
• High pressure cut-off switch
• Low pressure cycling clutch switch
• Powertrain Control Module (PCM).
(4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is 2.0 to 3.9
amperes with the electrical system voltage at 11.5 to
12.5 volts. This should only be checked with the work
area temperature at 21° C (70° F). If system voltage
is more than 12.5 volts, add electrical loads by turn-
ing on electrical accessories until the system voltage
drops below 12.5 volts.
(a) If the clutch coil current reading is four
amperes or more, the coil is shorted and should be
replaced.
(b) If the clutch coil current reading is zero, the
coil is open and should be replaced.
COMPRESSOR CLUTCH RELAY
RELAY TEST
The compressor clutch relay (Fig. 8) is located in
the Power Distribution Center (PDC). Refer to the
PDC label for relay identification and location.
Remove the relay from the PDC to perform the fol-
lowing 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
6 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 Relay Circuit Test in the Diagno-
sis and Testing section of this group. If not OK,
replace the faulty relay.
RELAY CIRCUIT TEST
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
(1) The relay common feed terminal cavity (30) is
connected to fused battery feed. There should be bat-
tery voltage at the cavity for relay terminal 30 at all
times. If OK, go to Step 2. If not OK, repair the open
circuit to the fuse in the PDC as required.
(2) The relay normally closed terminal (87A) is not
used in this application. Go to Step 3.
(3) The relay normally open terminal cavity (87) is
connected to the compressor clutch coil. There should
be continuity between this cavity and the A/C com-
pressor clutch relay output circuit cavity of the com-
XJ
HEATING AND AIR CONDITIONING
24 - 15
DIAGNOSIS AND TESTING (Continued)
pressor clutch coil wire harness connector. If OK, go
to Step 4. If not OK, repair the open circuit as
required.
(4) The relay coil battery terminal (86) is con-
nected to the fused ignition switch output (run/start)
circuit. There should be battery voltage at the cavity
for relay terminal 86 with the ignition switch in the
On position. If OK, go to Step 5. If not OK, repair the
open circuit to the fuse in the junction block as
required.
(5) The coil ground terminal cavity (85) is switched
to ground through the Powertrain Control Module
(PCM). There should be continuity between this cav-
ity and the A/C compressor clutch relay control cir-
cuit cavity of the PCM wire harness connector C
(gray) at all times. If not OK, repair the open circuit
as required.
DUAL FUNCTION HIGH PRESSURE SWITCH/
HIGH PRESSURE CUT-OFF SWITCH
Before performing diagnosis of the dual function
high pressure switch, or the high pressure cut-off
switch, verify that the refrigerant system has the cor-
rect refrigerant charge. See Refrigerant System
Charge in the Service Procedures section of this
group for more information.
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the high pressure switch wire harness
connector from the switch on the refrigerant system
fitting.
(3) On the dual function high pressure switch,
check for continuity between terminals C and D. On
the
two
terminal
switch,
check
for
continuity
between both terminals of the high pressure cut-off
switch. There should be continuity. If OK, test and
repair the A/C switch sense circuit as required. If not
OK, replace the faulty switch.
HEATER PERFORMANCE
Before performing the following tests, refer to
Group 7 - Cooling System for the procedures to check
the radiator coolant level, serpentine drive belt ten-
sion, radiator air flow and the radiator fan operation.
Also be certain that the accessory vacuum supply
line is connected at the engine intake manifold.
MAXIMUM HEATER OUTPUT
Engine coolant is delivered to the heater core
through two heater hoses. With the engine idling at
normal operating temperature, set the temperature
control knob in the full hot position, the mode control
switch knob in the floor heat position, and the blower
motor switch knob in the highest speed position.
Using a test thermometer, check the temperature of
the air being discharged at the heater-A/C housing
floor outlets. Compare the test thermometer reading
to the Temperature Reference chart.
Temperature Reference
Ambient Air Temperature
15.5° C
(60° F)
21.1° C
(70° F)
26.6° C
(80° F)
32.2° C
(90° F)
Minimum Air Temperature at
Floor Outlet
62.2° C
(144° F)
63.8° C
(147° F)
65.5° C
(150° F)
67.2° C
(153° F)
TERMINAL LEGEND
NUMBER
IDENTIFICATION
30
COMMON FEED
85
COIL GROUND
86
COIL BATTERY
87
NORMALLY OPEN
87A
NORMALLY CLOSED
Fig. 8 Compressor Clutch Relay
24 - 16
HEATING AND AIR CONDITIONING
XJ
DIAGNOSIS AND TESTING (Continued)
If the floor outlet air temperature is too low, refer
to Group 7 - Cooling System to check the engine cool-
ant temperature specifications. Both of the heater
hoses should be hot to the touch. The coolant return
heater hose should be slightly cooler than the coolant
supply heater hose. If the return hose is much cooler
than the supply hose, locate and repair the engine
coolant flow obstruction in the cooling system. Refer
to Group 7 - Cooling System for the procedures.
OBSTRUCTED COOLANT FLOW Possible loca-
tions or causes of obstructed coolant flow:
• Pinched or kinked heater hoses.
• Improper heater hose routing.
• Plugged heater hoses or supply and return ports
at the cooling system connections.
• A plugged heater core.
If proper coolant flow through the cooling system is
verified, and heater outlet air temperature is still
low, a mechanical problem may exist.
MECHANICAL PROBLEMS Possible locations or
causes of insufficient heat:
• An obstructed cowl air intake.
• Obstructed heater system outlets.
• A blend-air door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be
adjusted with the temperature control knob on the
heater-A/C control panel, the following could require
service:
• The heater-A/C control.
• The temperature control motor.
• The blend-air door.
• Improper engine coolant temperature.
LOW PRESSURE CYCLING CLUTCH SWITCH
Before performing diagnosis of the low pressure
cycling clutch switch, be certain that the switch is
properly installed on the accumulator fitting. If the
switch is too loose it may not open the Schrader-type
valve in the accumulator fitting, which will prevent
the switch from correctly monitoring the refrigerant
system pressure. Remember that lower ambient tem-
peratures, below about -1° C (30° F), during cold
weather will open the switch contacts and prevent
compressor operation due to the pressure/tempera-
ture relationship of the refrigerant.
Also verify that the refrigerant system has the cor-
rect refrigerant charge. See Refrigerant System
Charge in the Service Procedures section of this
group for more information.
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
(1) Disconnect and isolate the battery negative
cable.
(2) Unplug the low pressure cycling clutch switch
wire harness connector from the switch on the accu-
mulator fitting.
(3) Install a jumper wire between the two cavities
of the low pressure cycling clutch switch wire har-
ness connector.
(4) Connect a manifold gauge set to the refrigerant
system service ports. See Refrigerant System Service
Equipment and Refrigerant System Service Ports in
the Description and Operation section of this group
for more information.
(5) Connect the battery negative cable.
(6) Place the heater-A/C mode control switch knob
in any A/C position and start the engine.
(7) Check for continuity between the two terminals
of the low pressure cycling clutch switch. There
should be continuity 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 for the
procedures. If the refrigerant system is low or empty;
a leak at a refrigerant line, connector fitting, compo-
nent, or component seal is likely.
An electronic leak detector designed for R-134a
refrigerant, or a fluorescent R-134a leak detection
dye and a black light are recommended for locating
and confirming refrigerant system leaks. Refer to the
operating instructions supplied by the equipment
manufacturer for proper care and use of this equip-
ment.
An oily residue on or near refrigerant system lines,
connector fittings, components, or component seals
can indicate the general location of a possible refrig-
erant leak. However, the exact leak location should
be confirmed with an electronic leak detector prior to
component repair or replacement.
To detect a leak in the refrigerant system with an
electronic leak detector, perform one of the following
procedures:
SYSTEM EMPTY
(1) Evacuate the refrigerant system. See Refriger-
ant System Evacuate in this group for the proce-
dures.
XJ
HEATING AND AIR CONDITIONING
24 - 17
DIAGNOSIS AND TESTING (Continued)
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст