1998 ISUZU TROOPER check engine

HEATING AND VENTILATION 1A Ð 9
REMOVAL
Preparation:
·Disconnect the battery ground cable
·Drain engine coolant
1. Heater Unit
Refer to ÒHEATER UNITÓ removal procedure in this
section.
2. Duct
3. Case (Mode Control)
Do not remove link unit at this step.
4. Case (Temperature Control)
Separate two halves of core case.
Heater core
5. Heater Core
Heater core
6. Mode Door
Pull out the mode door while raising up the catch of
the door lever.
INSTALLATION
To install, follow the removal steps in the reverse order,
noting the following point:
1. Check that each mode door operates properly.

HEATING AND VENTILATION 1A Ð 11
REMOVAL
Preparation:
·Disconnect the battery ground cable
·Drain engine coolant
1. Heater Unit
Refer to ÒHEATER UNITÓ removal procedure in this
section.
2. Case (Mode Control)
Remove the case (Mode control) from heater unit.
3. Washer and Mode Main Lever
4. Rod
5. Mode Sub-Lever
Press the tab of the sub-lever inward, and take out the
sub-lever.
6. Door Lever
Pull out the door lever while raising up the catch of
the door lever.
INSTALLATION
To install, follow the removal steps in the reverse order,
noting the following points:
1. Apply grease to mode sub-lever and to the abrasive
surface of the heater unit.
2. After installing the link unit, check to see if the link
unit operates correctly.

HEATING AND VENTILATION 1A Ð 13
REMOVAL
Preparation:
·Disconnect the battery ground cable
·Drain engine coolant
1. Heater Unit
Refer to ÒHEATER UNITÓ removal procedure in this
section.
2. Case (Temperature Control)
Remove the case (Temperature control) from the
heater unit.
3. Rod
4. Sub-Lever
5. Door Lever
Pull out the door lever while raising up the catch of
the door lever.
6. Clip
INSTALLATION
To install, follow the removal steps in the reverse order,
noting the following points:
1. Apply grease to sub-lever and to the abrasive surface
of the heater unit.
2. After installing the link unit, check to see if the link
unit operates correctly.

AIR CONDITIONING 1B Ð 13
ACR41) Using the ACR4(HFC-134a Refrigerant Recovery/
Recycling/ Recharging/ System) or equivalent to
thoroughly discharge and recover the refrigerant.
ACR
4(115V 60Hz) : 5-8840-0629-0 (J-39500-A)
ACR4(220-240V 50/60Hz)
: 5-8840-0630-0 (J-39500-220A)
ACR
4(220-240V 50/60Hz Australian model)
: 5-8840-0631-0 (J-39500-220ANZ)
2) Remove and replace the defective part.
3) After evacuation, charge the air conditioning
system and check for leaks.
PRECAUTIONS FOR REPLACEMENT OR REPAIR OF
AIR CONDITIONING PARTS
There are certain procedure, practices and precautions
that should be followed when servicing air conditioning
systems:
·Keep your work area clean.
·Always wear safety goggle and protective gloves
when working on refrigerant systems.
·Beware of the danger of carbon monoxide fumes
caused by running the engine.
·Beware of discharged refrigerant in enclosed or
improperly ventilated garages.
·Always disconnect the negative battery cable and
discharge and recover the refrigerant whenever
repairing the air conditioning system.
·When discharging and recovering the refrigerant, do
not allow refrigerant to discharge too fast; it will draw
compressor oil out of the system.
·Keep moisture and contaminants out of the system.
When disconnecting or removing any lines or parts,
use plugs or caps to close the fittings immediately.
Never remove the caps or plugs until the lines or
parts are reconnected or installed.
·When disconnecting or reconnecting the lines, use
two wrenches to support the line fitting, to prevent
from twisting or other damage.
·Always install new O-rings whenever a connection is
disassembled.
·Before connecting any hoses or lines, apply new
specified compressor oil to the O-rings.
·When removing and replacing any parts which
require discharging the refrigerant circuit, the
operations described in this section must be
performed in the following sequence:
ON-VEHICLE SERVICE

1B Ð 20 AIR CONDITIONING
1) Make sure the evacuation process is correctly
completed.
2) Connect the center-hose of the manifold gauge to the
refrigerant container.
·Turn the charge valve handle counterclockwise to
purge the charging line and purge any air existing
in the center-hose of the manifold gauge.
3) Open the low-pressure hand valve and charge the
refrigerant about 200 g(0.44 lbs.).
·Make sure the high-pressure hand valve is closed.
·Avoid charging the refrigerant by turning the
refrigerant container upside down.
4) Close the low-pressure hand valve of the manifold
gauge.
·Check to ensure that the degree of pressure does
not charge.
5) Check the refrigerant leaks by using a HFC-134a leak
detector.
·If a leak occurs, repair the leak connection, and
start all over again from the first step of
evacuation.
6) If no leaks are found, open the low-pressure hand
valve of the manifold gauge.Then continue charging
refrigerant to the system.
·When charging the system becomes difficult:
(1) Run the engine at Idling and close the all
vehicle doors.
(2) A/C switch is ÒONÓ.
(3) Set the fan control knob (fan switch) to its
highest position.
WARNING
BE ABSOLUTELY SURE NOT TO OPEN THE HIGH-
PRESSURE HAND VALVE. SHOULD THE HIGH-
PRESSURE HAND VALVE BE OPENED, THE HIGH-
PRESSURE REFRIGERANT GAS WOULD FLOW
BACKWARD, AND THIS MAY CAUSE THE
REFRIGERANT CONTAINER TO BURST.
7) When the refrigerant container is emptied, use the
following procedure to replace it with a new
refrigerant container.
(1) Close the low pressure hand valve.
(2) Raise the needle upward and remove the charge
valve.
(3) Reinstall the charge valve to the new refrigerant
container.
(4) Purge any air existing in the center hose of the
manifold gauge.

AIR CONDITIONING 1B Ð 21
8) Charge the system to the specified amount and then
close the low-pressure hand valve.
Refrigerant Amount g(lbs.)
750 (1.65)
DELPH1HD6/HT6 g(lbs.)
600 (1.32)
·A fully charged system is indicated by the sight
glass on the receiver/driver being free of any.
bubbles(Refer to ÒReading Sight GlassÓ).
·Check the high and low pressure value of the
manifold gauge.
·Check for refrigerant leaks by using a HFC-134a
leak detector.
Immediately after charging refrigerant, both high and low
pressures are slightly high and to the left of the gauge, but
they settle down to the guide pressure valves as shown
below:
·Ambient temperature; 25 ~30¡C (77 ~86¡F)
·Guide pressure
High-pressure side;
Approx. 1373 Ð 1863 kPa (14 Ð 19 kgácm
2/ 199 Ð 270 PSI)
Low-pressure side;
Approx. 147 Ð 294 kPa (1.4 Ð 3.0 kgácm
2/ 21 Ð 43 PSI)
9) Close the low pressure hand valve and charge valve
of the refrigerant container.
10) Stop the air conditioning and the engine.
11) Disconnect the high and low pressure hoses from the
manifold gauge fittings.

1B Ð 22 AIR CONDITIONING
Almost transparent.
A flow of bubbles
can be seen, but
they disappear
when the throttle is
opened.
The sight glass provides accurate diagnosis only under the following conditions.
If the vehicle can be tested under these conditions, check the sight glass appearance and compare to the
chart.
* Engine speed Idling
* A/C switch ÒONÓ
* Blower fan operating at highest speed
* Air source selector lever at ÒRECIRCÓ
* Temperature control knob at coldest position
* Ambient temperature below 30¡C (86¡F) and humidity below 70% (See NOTE 1)
* High side pressure less than 1863 kPa (19 kgácm
2/ 270 PSI) (See NOTE 2)
NOTE 1
If the vehicle cannot be moved to a testing location that meets these specifications, then the sight glass
cannot be used for diagnosis. You must discharge and recover the refrigerant, then recharge the system
with the specified amount of refrigerant. Then continue checking the system performance.
NOTE 2
If the high side pressure is greater than stated, the sight glass cannot be used for diagnosis. You must
discharge and recover the refrigerant, then recharge the system with the specified amount of refrigerant.
Then continue checking system performance.
Reading Sight Glass
High and low
pressure pipe
temperature
Sight glass
condition
Air condi-
tioner cycle
condition
The high pressure
pipe is hot and the
low pressure pipe is
cold. There is a dis-
tinct difference in
temperature bet-
ween them.
OK
The high pressure
pipe is warm and
the low pressure
pipe is cool. There
is no great dif-
ference in tempera-
ture between them.
A flow of bubbles
always can be seen.
It appears some-
times transparent,
and sometimes
frothy.
NG
(Not enough
refrigerant)
There is little dif-
ference in tempera-
ture between the
high pressure pipe
and the low press-
ure pipe.
Something like fog
faintly can be seen.
NG
(Almost no
refrigerant)
The high pressure
pipe is hot and the
low pressure pipe is
slightly warm.
There is a difference
in temperature bet-
ween them.
Even at idle with the
fan at ÒHIÓ (with the
window fully open),
the bubbles cannot
be seen.
NG
(Too much
refrigerant)

1BÐ94 AIR CONDITIONING
Chart "A" : Check of Auto Amplifier Power Supply System
NOHarness disconnection or improper grounding.
NOHarness disconnection or improper grounding.
NOHarness disconnection or trouble on lighting
switch.
NOHarness disconnection or improper grounding.
Turn off ignition switch.
Power supply system is free of
trouble.
YES YES
YES YES
Is battery voltage present between chassis
harness connector terminal No.7
and ground?
I-32
Is battery voltage present between
chassis harness connector No.8
and ground?
I-32
Are chassis harness connector No.16
and body ground conducted?
B-18I-32
Turn on ignition switch (engine is started).
Turn on lighting switch.
Is battery voltage present between chassis
harness connector No.10 and
ground?
I-32