1998 ISUZU TROOPER relay

SERVICE INFORMATION 00 Ð 35
MAGNETIC CLUTCH DOES NOT RUN
·TURN THE STARTER SWITCH ON AND START THE
ENGINE.
·TURN THE FAN SWITCH ON.
·DOES THE BLOWER MOTOR RUN?
YESNO
REFER TO THE DIAGNOSIS PROCEDURE FOR
ÒBLOWER MOTOR DOES NOT RUNÓ.·IS THE FUSE C-20 (10A) NORMAL?
YESNO
REPLACE THE FUSE.·DISCONNECT THE A/C SWITCH CONNECTOR AND
REMOVE THE A/C SWITCH.
·IS THE A/C SWITCH NORMAL?
YESNO
YESNO
REPAIR AN OPEN CIRCUIT BETWEEN THE
FUSE C-20 AND I23-2.·REINSTALL THE A/C SWITCH AND DISCONNECT THE DUAL
PRESSURE SWITCH (OR TRIPLE PRESSURE SWITCH) CON-
NECTOR C25.
·TURN THE A/C SWITCH ON.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR C25-1?
YESNO
REPLACE THE SWITCH.·RECONNECT THE CONNECTOR C25 AND DISCONNECT THE
A/C THERMO RELAY CONNECTOR X5.
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CONNEC-
TOR C25-2 AND X5-1?
YESNO
REPAIR AN OPEN CIRCUIT BETWEEN I23-6
AND C25-1.·IS THE DUAL PRESSURE SWITCH (OR TRIPLE PRESSURE
SWITCH) NORMAL?
YESNO
REPAIR OR REPLACE THE SWITCH.·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR I23-2?

00 Ð 36 SERVICE INFORMATION
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR X5-2?REPAIR AN OPEN CIRCUIT.
YESNO
·IS THE A/C THERMO RELAY NORMAL?REPAIR AN OPEN CIRCUIT BETWEEN THE
FUSE C-20 AND X5-2.
YESNO
·DISCONNECT THE ELECTRONIC THERMOSTAT CONNEC-
TOR I42.
·IS THE BATTERY VOLTAGE APPLIED AT HARNESS SIDE
CONNECTOR I42-3?
YESNO
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR X5-3 AND I42-1?REPAIR AN OPEN CIRCUIT BETWEEN I23-6
AND I42-3.
YESNO
REPAIR AN OPEN CIRCUIT.
YESNO
·IS THERE CONTINUITY BETWEEN HARNESS SIDE CON-
NECTOR I42-2 AND THE GROUND?REPAIR AN OPEN CIRCUIT.
REPLACE THE RELAY.
·DIS CONNECT THE MAGNETIC CLUTCH CONNECTOR E27.
·CONNECT THE BATTERY WITH MAGNETIC CLUTCH SIDE
CONNECTOR E27-1.
·DOES THE MAGNETIC CLUTCH.
YESNO
REPAIR OR REPLACE THE MAGNETIC CLUTCH.·REPAIR AN OPEN CIRCUIT BETWEEN X5-4 AND E27-1.

SERVICE INFORMATION 00 Ð 37
CONDENSER FAN
When the cycling switch, which controls the
condenser fan of the triple pressure switch while
the A/C switch is on, senses the refrigerant pressureand the condenser fan turns on, the motor operates
via the condenser fan relay.
123
45 6
4
13
24
1
FAN SW.
B-2
OFF
I-18
I-18
B-1
(LHD)
(RHD)
X-19
1
3
4
5
RELAY;
CONDENSER
FAN
4TRIPLE
PRESSURE
SWITCH
3
1CONDENSER
FAN
2M
C-75 C-39
C-25
FL-4
30A
CONDENSER FANFL-1
80A
MAIN
2
6
1
I-23
RELAY; A/C
A/C SWITCH
2
C-39C-75C-25
I-23X-19
123 4
567 843
872
61
5
121 21
2 34
213
5 4612
34
D08RWD70

00 Ð 38 SERVICE INFORMATION
CONDENSER FAN DOES NOT RUN
YESNO
·DOES A/C SYSTEM OPERATE CORRECTLY?
·IS FL-4 (30A) FUSE OK?CHECK A/C SYSTEM AND REPAIR AS NECESSARY
YESNO
·IS CONDENSER FAN RELAY (X-19) OK?REPLACE
REPLACE
YESNO
·IS TRIPLE PRESSURE SWITCH (CYCLING SWITCH SIDE)
OK?
REPLACE
YESNO
·IS CONDENSER FAN MOTOR OK?
REPLACE
YESNO
·CHECK TO SEE IF CONTINUITY BETWEEN FL-4 (30A)
FUSE AND CHASSIS SIDE RELAY TERMINAL NO. X19-1.
REPLACE
YESNO
·CHECK TO SEE IF CONTINUITY BETWEEN CHASSIS SIDE
CONNECTOR TERMINAL NO. I23-6 AND NO. C25-3.
OPEN CIRCUIT
YESNO
·CHECK TO SEE IF CONTINUITY BETWEEN CHASSIS SIDE
CONNECTOR TERMINAL NO. C25-4 AND CHASSIS SIDE
RELAY TERMINAL NO. X19-4.
OPEN CIRCUIT
YESNO
·CHECK TO SEE IF CONTINUITY BETWEEN CHASSIS SIDE
RELAY TERMINAL NO. X19-5 AND CHASSIS SIDE
CONNECTOR TERMINAL NO. I18-4.
OPEN CIRCUIT
YESNO

SERVICE INFORMATION 00 Ð 39
·CHECK TO SEE IF CONTINUITY BETWEEN CHASSIS SIDE
RELAY TERMINAL NO. X19-3 AND CHASSIS SIDE
CONNECTOR TERMINAL NO. C75-1.
YESNO
OPEN CIRCUITPOOR GROUND OR OPEN CIRCUIT BETWEEN CHASSIS
SIDE CONNECTOR TERMINAL NO. C75-2 AND BODY
GROUND (NO. C39-7)
CONDENSER FAN DOES NOT STOP
·IS CONDENSER FAN RELAY (X-19) OK?
YESNO
REPLACETRIPLE PRESSURE SWITCH (CYCLING SWITCH SIDE)
DEFECTIVE
REPLACE TRIPLE PRESSURE SWITCH

SERVICE INFORMATION 00 Ð 41
I-18 I-23
123456126
OFF
1
FAN SW. 2
3
4
OFF
A/C SW.
ON
FAN CONTROL KNOB (FAN SWITCH) AND A/C
SWITCH
INDIVIDUAL INSPECTION
Check for continuity between fan switch and A/C switch
side connector terminals.
2
65 4 31362
51
4

I-23I-18
I-23I-18
5
A/C SW. BEZEL
ILLUMI-
NATION
FAN SW. OFF1
2
3
4 32 6 1253641
HEATER & A/C, THERMOSTAT, COMPRESSOR,
CONDENSER FAN AND CERAMIC HEATER RELAY
Check for continuity between the relay terminals.
2Ð 4..... No continuity
(When battery voltage is applied between 1Ð 3)
2Ð 4..... Continuity
2
2
1
144
3
3
Terminal
No. SW.
position
DUAL PRESSURE SWITCH
21
Disconnect pressure switch connector and check for
continuity between pressure switch side connector
terminals.

AIR CONDITIONING 1B Ð 7
EVAPORATOR
The evaporator cools and dehumidifies the air
before the air enters the vehicle. High-pressure
liquid refrigerant flows through the expansion valve
(1) into the low-pressure area of the evaporator (2).
The heat in the air passing through the evaporator
core is lost to the cooler surface of the core, thereby
cooling the air.
As heat is lost between the air and the evaporator
core surface, moisture in the vehicle condenses on
the outside surface of the evaporator core and is
drained off as water.
When the evaporator malfunctions, the trouble will
show up as inadequate supply of cool air. The
cause is typically a partially plugged core due to
dirt, or a malfunctioning blower motor.
The evaporator core with a laminate louver fin is a
single-sided tank type where only one tank is
provided under the core.
ELECTRONIC THERMOSTAT
The thermostat consists of the thermosensor (1)
and thermostat unit (4) which functions electrically
to reduce the noises being generated while the
system is in operation.
The electronic thermosensor (1) is mounted at the
evaporator core (2) outlet and senses the
temperature of the cool air from the evaporator (3).
Temperature signals are input to the thermostat
unit. This information is compared by the thermo
unit and the results in output to operate the A/C
Thermostat relay and turn the magnetic clutch
ÒONÓ or ÒOFFÓ to prevent evaporator freeze-up.
A characteristic of the sensor is that the resistance
decreases as the temperature increases and the
resistance increases as the temperature decreases.
REFRIGERANT LINE
Restrictions in the refrigerant line will be indicated by:
1. Suction line; A restricted suction line will cause
low suction pressure at the compressor, low
discharge pressure and little or not cooling.
2. Discharge line; A restriction in the discharge line
generally will cause the discharge line to leak.
3. Liquid line; A liquid line restriction will be
evidenced by low discharge and suction
pressure and insufficient cooling.
Refrigerant flexible hoses that have a low
permeability to refrigerant and moisture are used.
These low permeability hoses have a special nylon
layer on the inside.
SERVICE CHARGE VALVES
The charging hoses have a quick-joint type fitting,
to reduce refrigerant loss during removal and
installation.
12
3
4
Reinforcement layer(Polyester) Resin layer(Nylon)
Internal rubber layer
External rubber layer
1
2
874RY00003874RX022

AIR CONDITIONING 1B Ð 9
852RY00008
This illustration is based on RHD
A/C switch
Drain hose
Suction line (Low-pressure hose)
Discharge line (High-pressure hose)Compressor bracket
Pressure
switch
Receiver/drier
Compressor
Relay
Condenser assembly Drive belt O-ring Suction line
(Low-pressure pipe) Evaporator assembly
Liquid line(High-pressure pipe)
Liquid line
(High-pressure pipe)
4JG2 (R/LHD)