ISUZU TROOPER 1998 Service Repair Manual

AIR CONDITIONING 1B Ð 5
With some compressors the differential between
the intake pressure and discharge pressure
generated while the compressor is operating is
used for lubrication instead of an oil pump.
The specified amount of the DKV-14D, DKS-15CH
and HD6 compressors oil is 150cc (4.2 Imp fl oz).
Also, compressor oil to be used varies according to
the compressor model. Be sure to avoid mixing
two or more different types of oil.
If the wrong oil is used, lubrication will be poor and
the compressor will seize or malfunction.
The magnetic clutch connector is a waterproof type.
MAGNETIC CLUTCH
The compressor is driven by the drive belt from the
crank pulley of the engine. If the compressor is
activated each time the engine is started, this
causes too much load to the engine. The magnetic
clutch transmits the power from the engine to the
compressor and activates it when the air
conditioning is ÒONÓ. Also, it cuts off the power
from the engine to the compressor when the air
conditioning is ÒOFFÓ. (Magnetic clutch repair
procedure can be found in Section 1D.)
CONDENSER
The condenser assembly in front of the radiator,
which carry the refrigerant and cooling fins to
provide rapid transfer of heat.
Also, it functions to cool and liquefy the high-
pressure and high-temperature vapor sent from the
compressor by the radiator fan or outside air.
A condenser may malfunction in two ways: it may
leak, or it may be restricted. A condenser restriction
will result in excessive compressor discharge
pressure. If a partial restriction is present, the
refrigerant expands after passing through the
restriction.
Thus, ice or frost may from immediately after the
restriction. If air flow through the condenser or
radiator is blocked, high discharge pressures will
result. During normal condenser operation, the
refrigerant outlet line will be slightly cooler than the
inlet line.
The vehicle is equipped with the condenser of the
parallel flow type condenser. A larger thermal
transmission area on the inner surface of the tube
allows the radiant heat to increase and the
ventilation resistance to decrease.
The refrigerant line connection has a bolt at the
block joint, for easy servicing.
RECEIVER/DRIER
The receiver/drier performs four functions;
·As the quantity of refrigerant circulated varies
depending on the refrigeration cycle conditions,
sufficient refrigerant is stored for the refrigera-
tion cycle to operate smoothly in accordance
with fluctuations in the quantity circulated.
·The liquefied refrigerant from the condenser is
mixed with refrigerant gas containing air
bubbles. If refrigerant containing air bubbles is
sent to the expansion valve, the cooling
capacity will decrease considerably. Therefore,
the liquid and air bubbles are separated and
only the liquid is sent to the expansion valve.
·The receiver/drier utilizes a filter and dryer to
remove the dirt and water mixed in the cycling
refrigerant.
·The sight glass, installed atop the receiver/
drier, show the state of the refrigerant.
A receiver/drier may fail due to a restriction inside
the body of the unit. A restriction at the inlet to the
receiver/drier will cause high pressures.
Outlet restrictions will be indicated by low pressure
and little or no cooling. An excessively cold
receiver/ drier outlet may indicate a restriction.
The receiver/drier of this vehicle is made of
aluminum with a smaller tank. It has 300 cc
(8.5 Imp fl oz) refrigerant capacity.
The refrigerant line connection has a bolt at the
block joint, for easy servicing.
DKV-14D TYPE
DKS-15CH TYPE
HD6 TYPE
Magnetic clutch
CompressorSuction side
Discharge side
Compressor Magnetic clutch
852RW031 871RY00012
871RY00011

1B Ð 6 AIR CONDITIONING
DUAL PRESSURE SWITCH
The dual pressure switch is installed on the upper
part of the receiver/drier, to detect excessively high
pressure (high pressure switch) and prevent
compressor seizure due to the refrigerant leaking
(low pressure switch), switching the compressor
ÒONÓ or ÒOFFÓ as required.
The pressure switch connector is waterproof type.
·Low-pressure control kpa (kgácm
2/ PSI)
Compressor
ON: 205.9 ± 30 (2.1 ± 0.3 / 30 ± 4)
(Except 6VD1 / 6VE1, LHD model)
186 ± 30 (1.9 ± 0.3 / 27 ± 4)
(only for 6VD1 / 6VE1, LHD model)
OFF: 176 ± 20 (1.8 ± 0.2 / 26 ± 3)
·High-pressure control
Compressor
ON: 2354 ± 196 (24.0 ± 2.0 / 341 ± 28)
OFF: 2942 ± 196 (30.0 ± 2.0 / 427 ± 28)
TRIPLE PRESSURE SWITCH
Triple pressure switch is installed atop the receiver/
drier. This switch is constructed with a unitized type
of two switches. One of them is a low and high
pressure switch (Dual pressure switch) to switch
ÒONÓ or ÒOFFÓ the magnetic clutch as a result of
irregularly high-pressure or low-pressure of the
refrigerant. The other one is a medium pressure
switch (Cycling switch) to switch ÒONÓ or ÒOFFÓ
the condenser fan sensing the condenser high side
pressure.·Low-pressure control kpa (kgácm
2/PSI)
Compressor
ON: 186 ± 30 (1.9 ± 0.3 / 27 ± 4)
OFF: 176 ± 20 (1.8 ± 0.2 / 26 ± 3)
·Medium-pressure control
Condenser fan
ON: 1471 ± 98 (15.0 ± 1.0 / 213 ± 14)
OFF: 1079 ± 98 (11.0 ± 1.0 / 156 ± 14)
·High-pressure control
Compressor
ON: 2354 ± 196 (24.0 ± 2.0 / 341 ± 28)
OFF: 2942 ± 196 (30.0 ± 2.0 / 427 ± 28)
EXPANSION VALVE
This expansion valve (1) is internal pressure type
and it is installed at the evaporator intake port.
The expansion valve converts the high pressure
liquid refrigerant sent from the receiver/drier to a
low pressure liquid refrigerant by forcing it through
a tiny port before sending it to the evaporator (2).
This type of expansion valve consists of a
temperature sensor, diaphragm, ball valve, ball
seat, spring adjustment screw, etc.
The temperature sensor contacts the evaporator
outlet pipe, and converts changes in temperature to
pressure. It then transmits these to the top chamber
of the diaphragm.
The refrigerant pressure is transmitted to the
diaphragms bottom chamber through the external
equalizing pressure tube.
The ball valve is connected to the diaphragm. The
opening angle of the expansion valve is determined
by the force acting on the diaphragm and the spring
pressure.
The expansion valve regulates the flow rate of the
refrigerant. Accordingly, when a malfunction occurs
to this expansion valve, both discharge and suction
pressures get low, resulting in insufficient cooling
capacity of the evaporator.
Pressure switch
Receiver/Drier
Triple pressure switch
Condenser fan Condenser
1
2
875RY00003874RY00003

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

1B Ð 8 AIR CONDITIONING
AIR CONDITIONING PARTS
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) Pressure Switch
(3) Receiver Drier
(4) Discharge Line (High-Pressure Hose)
(5) Suction Line (Low-Pressure Hose)
(6) Compressor(7) Condenser Assembly
(8) Serpentine Belt
(9) Compressor Bracket
(10) Drain Hose
(11) Evaporator Assembly
(12) O-ring
9
61
1
4
5
1112
10
2
3
7
8
6VD1/6VE1 (RHD)
852RY00006

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)

1B Ð 10 AIR CONDITIONING
96 12
54 11
13
1014
2 1
3
8 7
852RY00005
4JX1 (RHD)
Legend
(1) Liquid Line (High- Pressure Pipe)
(2) Pressure Switch
(3) Receiver Drier
(4) Compressor Bracket
(5) Discharge Line (High-Pressure Hose)
(6) Suction Line (Low-Pressure Hose)
(7) Compressor(8) Condenser Assembly
(9) O-ring
(10) Insulator Pipe
(11) Suction Line (Low Pressure Pipe)
(12) Drain Hose
(13) Evaporator Assembly
(14) A/C Switch

AIR CONDITIONING 1B Ð 11
13 12
11
10
8
732
91 1
5
4
6
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) Pressure Switch
(3) Receiver Drier
(4) Discharge line (High-Pressure Hose)
(5) Suction Line (Low-Pressure Hose)
(6) Compressor(7) Condenser Assembly
(8) Condenser Fan
(9) Serpentine Belt
(10) Compressor Bracket
(11) Drain Hose
(12) Evaporator Assembly
(13) Suction Line (Low-Pressure Pipe)
852RY00012
6VD1/6VE1 (LHD)

1B Ð 12 AIR CONDITIONING
Legend
(1) Liquid Line (High-Pressure Pipe)
(2) O-ring
(3) Compressor
(4) Discharge line (High-Pressure Hose)
(5) Pressure Switch
(6) Receiver Drier(7) Condenser Assembly
(8) Serpentine Belt
(9) Relay
(10) Drain Hose
(11) Suction Line (Low-pressure Hose)
(12) Evaporator Assembly
(13) A/C Switch
12
13
4
2
3
5
6
7
8
911
10
1
Delphi Harrison (LHDáV6)
852RW009

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 14 AIR CONDITIONING
REPAIR OF REFRIGERANT LEAKS
Refrigerant Line Connections
Install new O-rings, if required. When disconnecting or
connecting lines, use two wrenches to prevent the
connecting portion from twisting or becoming damaged.
When connecting the refrigerant line at the block joint,
securely insert the projecting portion of the joint portion
into the connecting hole on the unit side and secure with a
bolt.O-ring
Block joint
Apply specified compressor oil to the O-rings prior to
connecting.
CAUTION:
Compressor (PAG) oil to be used varies according to
compressor model. Be sure to apply oil specified for the
model of compressor.
O-rings must be closely aligned with raised portion of
refrigerant line.
Correct Incorrect Incorrect