clutch ISUZU TROOPER 1995 User Guide

The refrigeration cycle includes the following four
processes as the refrigerant changes repeatedly
from liquid to gas and back to liquid while circulat­
ing.
EVAPORATION
The refrigerant is changed from a liquid to a gas in­
side
the evaporator. The refrigerant mist that enters
the evaporator vaporizes readily. The liquid refrige­
rant removes
the required quantity of heat (latent
heat of vaporization) from the air around the evap­
orator core cooling fins and rapidly vaporizes.
Removing the heat cools the air, which is then
radiated
from the fins and lowers the temperature of
the air inside the vehicle.
The refrigerant liquid sent from the expansion valve
and the vaporized refrigerant gas are both present
inside the
evaporator and the liquid is converted to
gas.
With this change from liquid to gas, the pressure
inside
the evaporator must be kept low enough for
vaporization to occur at a lower temperature.
Because of that, the vaporized refrigerant is sucked
into the compressor.
COMPRESSION
The refrigerant is compressed by the compressor
until it is easily liquefied at normal temperature.
The vaporized
refrigerant in the evaporator is sucked
into the compressor. This action maintains the
refrigerant inside the evaporator at a low pressure
so
that it can easily vaporize, even at low tempera­
tures close to ooc (32°F).
Also, the refrigerant sucked into the compressor is
compressed inside the
cylinder to increase the
pressure and temperature to values such that the
refrigerant can easily liquefy at normal ambient
temperatures.
CONDENSATION
The refrigerant inside the condenser is cooled by the
outside air and changes from gas to liquid.
The high temperature, high pressure gas coming
from the compressor is cooled and liquefied by the
condenser with outside air and accumulated in the
receiver/drier. The heat radiated to the outside air by
the high temperature, high pressure gas in the
compressor is called heat of condensation. This is
the total quantity of heat (heat of vaporization) the
refrigerant removes
from the vehicle interior via the
evaporator and the work (calculated as the quantity
of heat) performed for compression.
'-' EXPANSION
The expansion valve lowers the pressure of the
refrigerant liquid so that it can easily vaporize.
AIR CONDITIONING 1 B -3
The process of lowering the pressure to encourage
vaporization before the
liquefied refrigerant is sent
to the evaporator is called expansion. In addition,
the expansion valve controls the flow rate of the
refrigerant liquid while decreasing the pressure.
That is, the quantity of refrigerant liquid vaporized
inside
the evaporator is determined by the quantity
of heat which must be removed at a prescribed
vaporization temperature.
It is important that the
quantity of refrigerant be controlled to exactly the
right value.
COMPRESSOR
It compressor performs two main functions:
It compresses low-pressure and low-temperature
refrigerant vapor from the evaporator into high­
pressure and high-temperature
refrigerant vapor to
the condenser. And it pumps refrigerant and
refrigerant
oil through the air conditioning system.
This vehicle is equipped with five-vane rotary com­
pressor.
The
thermo sensor is installed to the front head of
the compressor to protect it by stopping its
operation when the refrigerant gas is insufficient or
when the temperature is abnormally high.
• OFF ...... 160 ±soc (320.0 ± 9.0°F)
• ON
...... 135 ±soc (27S.O ± 9.0°F)
The specified amount of the compressor oil is 1SOcc
(S.O fl.oz.).
The oil used in the HFC-134a system compressor
differs from that used in R-12 systems.
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 ac­
tivated 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 com­
pressor and activates it when the air conditioning is
"ON". Also, it cuts off the power from the engine to
the compressor when the air conditioning is "OFF".
(Magnetic clutch repair procedure can be found in
Section 1 D.)

1 B - 4 AIR CONDITIONING
Compressor
Thermosensor
Magnetic clutch
Fig. 18-2
CONDENSER
The condenser assembly is located in front of the
radiator. It carries 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 restric­
tion 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 re­
frigerant outlet line will be slightly cooler than the
inlet line.
The vehicle is equipped with 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 bub­
bles. 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 inlet to the re­
ceiver/drier
will cause high pressures.
Outlet restrictions will be indicated by low pressure
and
little or no cooling. An excessively cold re­
ceiver/drier
outlet may indicate a restriction.
The receiver/drier
of this vehicle is made of alu­
minum with a smaller tank. It has 300 cc refrigerant
capacity.
The
refrigerant line connection has a bolt at the
block joint, for easy servicing.
PRESSURE SWITCH
The pressure switch (Dual pressure switch) is in­
stalled 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), so that the
compressor is able to turned "ON" or "OFF".
The pressure characteristics of HFC-134a refrigerant
differ from those of R-12. Thus, the pressure switch
operation for HFC-134a systems has been changed
from R-12.
• Compressor ON · OFF (kPa/psi)
Low-pressure control
ON: 186.3 ± 29.4 (27.0 ± 4.3)
OFF: 176.5 ± 19.6 (25.6 ± 2.8)
High-pressure
control
ON: 2059.4 ± 196.1 (341.3 ± 28.4)
OFF: 2942.0 ± 196.1 (426.6 ± 28.4)

1 B-6 AIR CONDITIONING
ELECTRONIC THERMOSTAT
The thermostat consists of the thermosensor and
thermostat unit which functions electrically to
reduce the noises being generated while the system
is in operation.
The
electronic thermosensor is mounted at the
evaporator core outlet and senses the temperature
of the cool air from the evaporator. 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 "ON" or "OFF"
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.
Thermosensor Clip
Evaporator
unit
Fig. 18-6
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 per­
meability to refrigerant and moisture are used.
These
low permeability hoses have a special nylon
layer on the inside.
Refrigerant
lines given in the illustration (Fig. 1 B-8).
Resin layer (Nylon)
Reinforcement layer (Polyester)
External rubber layer
Fig. 1 B-7
•

DIAGNOSIS
AIR CONDITIONING CYCLE DIAGNOSIS
TROUBLE POSSIBLE CAUSE
No cooling or 1. Magnetic clutch does not run
insufficient cooling
2. Compressor is not rotating properly
• Drive belt loosened or broken
• Magnetic clutch face is not
clean and slips
• Incorrect clearance between
magnetic
drive plate and pulley
• Compressor oil leaks from shaft
seal
or shell
• Compressor seized
3. Insufficient or excessive charge of
refrigerant
4. Leaks in the refrigerant system
5. Condenser clogged or insufficient
radiation
6. Temperature control link unit of the
heater
unit defective
7. Unsteady operation due to foreign
substance in expansion valve
8. Poor operation of electronic
thermostat
Insufficient velocity 1. Evaporator clogged or frosted
of cooling air
2. Air leaking from cooling unit or air
duct
3. Blower motor does not rotate prop-
erly
AIR CONDITIONING 1 B - 9
CORRECTION
• Refer to "MAGNETIC CLUTCH
• DIAGNOSIS" in this section
• Adjust the drive belt to the specified
tension
or replace the drive belt
• Clean the magnetic clutch face or
replace
• Adjust the clearance (Refer to Sec-
• tion 1 D "COMPRESSOR OVER-
HAUL")
• Replace the compressor
• Replace the compressor
• Discharge and recover refrigerant.
Recharge
to specified amount.
• Check refrigerant system for leaks
and repair
as necessary
Discharge and recover refrigerant.
Recharge
to specified amount.
• Clean the condenser or replace as
necessary
• Repair the link unit
• Replace the expansion valve
• Check electronic thermostat and
replace
as necessary
• Check evaporator core and replace
or clean the core
• Check evaporator and duct connec-
tion, then repair as necessary
• Refer to Section 1A for "FAN CON-
TROL KNOB
(FAN SWITCH) DIAG-
NOSIS"
* For the execution of the charging and discharging operation in the table above, refer to the "RECOVERY,
RECYCLING, EVACUATING
AND CHARGING" in this section.

18-14 AIR CONDITIONING
MAGNETIC CLUTCH DIAGNOSIS
When the air conditioning switch and the fan
control knob (fan switch) are turned on with the
engine running, current flows through the
thermostat and the compressor relay to activate the
magnetic clutch.
The air conditioning can be stopped by turning off
the air conditioning switch or the fan control knob
(fan switch). However, even when the air
conditioning is in operation, the electronic
thermostat, the pressure switch or the Engine
BATTER y
~
A/C SW.
FAN SW.
FL-1 BOA MAIN -.Y""'
I
RELAY; HEATER&A/C (8-36)
-
·~
~-----;::: -
I ,--<> -v--ro 2
I 6
! -&r ro 1 l ~ .... --~-'---
11-231
r-g-I 4
I~ 0 I 2 1
l __ 9_ OFF -
lli!J
~
r-----3 I
I 1
I 2 -
ELECTRONIC ~ THERMOSTAT
l __ _
C-20 10A Jd.C
RELAY; RESTART
-=-
ECM -Engine Control Module , NC -Air Conditioning
Control Module (ECM) is used to stop the air
conditioning temporarily by turning off the
magnetic clutch in the prearranged conditions to
reduce the engine load which is being caused by
the rise in the engine coolant temperature, and the
acceleration of the vehicle, etc.
For
the inspection of the relays, switches and units
in the flow chart, refer to "INDIVIDUAL
INSPECTION."
,....-1
2 ......_
.....-=.-2
40. r-
1v-
3
......._ =--
~
I ___ j
PRESSURE
SW.
ECMIC91
~
---2 ----l
•o--
1v-
3
-~-@]
~1
L
[ill
I
I RELAY; COMPRESSOR
I
I I ___ j
ECMIA21 ~
:=:>
MAGNETIC
CLUTCH
,.----I In_ r-r
A1 Kl ., .. ...... A& .. A7 AI ld A10 A11A12 .... •• ., .. a1o an 112
'It!
~
~
Fig.1B-11

AIR CONDITIONING 1 B -15
MAGNETIC CLUTCH DOES NOT RUN
• ARE NO. C-20 (10A) FUSE AND NO. C-19 (25A) FUSE OK?
•
ARE HEATER & A!C (B-36), THERMOSTAT (X-5) AND
COMPRESSOR (X-7) RELAYS OK?
•
ARE AIR CONDITIONING SWITCH AND FAN CONTROL
KNOB
(FAN SWITCH) OK?
•
TURN THE IGNITION SWITCH "ON" (ENGINE IS RUNNING)
• AIR CONDITIONING SWITCH
AND FAN CONTROL KNOB
(FAN SWITCH) "ON"
• CHECK TO SEE IF BATTERY VOLTAGE IS PRESENT AT
CHASSIS SIDE CONNECTOR TERMINAL NO. E3-1
• CHECK TO SEE IF BATTERY VOLTAGE IS PRESENT AT
CHASSIS SIDE CONNECTOR TERMINAL NO. C25-1
Continued on next page.
SWITCH DEFECTIVE OR INSUFFICIENT
REFRIGERANT
• CHECK TO
SEE IF CONTINUITY BETWEEN
COMPRESSOR SIDE CONNECTOR
TERMINAL NO.
E3-1 AND MAGNETIC
CLUTCH SIDE CONNECTOR TERMINAL

1 B -24 AIR CONDITIONING
COMPRESSOR
Compressor bracket
Idle pulley
4
3
2
Fig. 1 B-24
1••1 REMOVAL
Preparation:
Disconnect the battery ground cable
Discharge and recover refrigerant (Refer to "RE­
FRIGERANT RECOVERY"
in this section.)
1. Magnetic clutch harness connector
2. Radiator fan shroud
3. Radiator fan
• When the fan is removed, be sure to tighten
the fan fixing nuts temporarily to their orig­
inal positions.
4. Drive belt
• Loosen idle pulley center nut and tension
adjustment bolt, then remove the drive belt
(Fig. 18-25).
Center nut
Idle pulley
Compressor
To Evaporator
I
5
Removal steps 1. Magnetic clutch harness
connector
2. Radiator fan shroud
3. Radiator fan 4. Drive belt 5. Refrigerant line connector
6. Compressor
Installation steps
To
install, follow the removal steps in the reverse order.
Fig. 1 B-25
•

5. Refrigerant line connector
• When removing the line connector, the con­
necting part
should immediately be plugged
or capped to prevent foreign matter from
being mixed into the line.
6. Compressor
l••liNSTALLATION
6. Compressor
• Tighten the compressor fixing bolts to the
specified torque.
~~~ Torque N·m (lb·ft) 19 (14)
5. Refrigerant line connector
• Tighten the refrigerant line connector fixing
bolts to the specified torque.
~~~ Torque N·m (lb.ft) 15 (11)
• 0-rings cannot be reused. Always replace
with new ones.
1~1 • Be sure to apply new compressor oil to the 0-
rings when connecting refrigerant lines.
4. Drive belt
r:cJ • Push the drive belt with the force of 22 lbs.,
L:D and adjust the drive belt tension by tighten-
ing idle pulley tension adjustment bolt, until
the 10 mm (0.4 in) deflection of the belt is
obtained. Then
tighten the pulley center nut
(Fig. 1 B-26).
~~I __ T_o_r_!q_ue.:...._ __ N_·m__;_(l_b_·ft....:..) _ __,_ __ 4_2....:..(_31_)_
3. Radiator fan
2. Radiator fan shroud
1. Magnetic clutch harness connector
Tension pulley
Crank pulley 10 kg (22 lbs.)
Fig. 18-26
AIR CONDITIONING 1 B -25
NEW COMPRESSOR INSTALLATION
The new compressor is filled with 150cc (5.0 fl.oz.) of
compressor oil and nitrogen gas. When mounting
the compressor on the vehicle, perform the follow­
ing steps;
1. Gently release nitrogen gas from the suction
side
ofthe new compressor (Fig. 18-27).
• Take care not to let the compressor oil flow
out.
• Inspect 0-rings and replace if necessary.
Fig. 18-27
2. Turn the compressor several times by hand and
release
the compressor oil in the rotor.
3. When installing on a new system, the compres­
sor should be installed as it is. When installing
on a used system, the compressor should be
installed after adjusting the amount of com­
pressor oil.
(Refer to Section 10 "COMPRESSOR OVER­
HAUL" for General Information.)

COMPRESSOR OVERHAUL 1 D - 1
SECTION 10
COMPRESSOR OVERHAUL
CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . 1 D-1
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
D-2
General Information . . . . . . . . . . . . . . . . . . . . 1 D-3
Compressor Oil . . . . . . . . . . . . . . . . . . . . . . 1 D-3
Service Procedures . . . . . . . . . . . . . . . . . . . . . 1D-5
Magnetic Clutch Assembly . . . . . . . . . . . . . 1 D-5
Main Data and Specifications . . . . . . . . . . . . . 1 D-8
General Specifications . . . . . . . . . . . . . . . . . 1 D-8
Torque Specifications . . . . . . . . . . . . . . . . . 1 D-8
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . 1D-9
GENERAL DESCRIPTION
When servicing the compressor, keep dirt or foreign
material from getting on or into the compressor
parts and system. Clean tools and a clean work area
are
important for proper service. The compressor
connections and the outside of the compressor
should be cleaned before any "On-Vehicle" repair,
or before removal of the compressor. The parts must
be kept clean at all times and any parts to be
reassembled
should be cleaned with Trichloro­
ethane, naphtha, kerosene, or equivalent solvent,
and
dried with dry air. Use only lint free cloths to
wipe parts.
The
operations described below are based on bench
overhaul
with compressor removed from the
vehicle, except as noted. They have been prepared
in
order of accessibility of the components. When
the compressor is removed from the vehicle for
servicing, the oil remaining in the compressor
should be discarded and new compressor oil added
to the compressor.
Magnetic clutch assembly repair procedures require
that the system be discharged of refrigerant. (Refer
to Section 1 B for "REFRIGERANT RECOVERY".)
Compressor malfunction will appear in one of four
ways: noise, seizure, leakage or low discharge
pressure. Resonant
compressor noises are not
cause for alarm; however, irregular noise or rattles
may indicate broken parts or excessive clearances
due to wear. To check seizure, de-energize the
magnetic clutch and check to see if the drive plate
can be rotated.
If rotation is impossible, the com­
pressor is seized. Low discharge pressure may be
due to a faulty internal seal of the compressor, or a
restriction in the compressor.
Low discharge pres­
sure
may also be due to an insufficient refrigerant
charge
or a restriction elsewhere in the system.
These possibilities
should be checked prior to
servicing the compressor. If the compressor is
inoperative,
but is not seized, check to see if current
is being supplied to the magnetic clutch coil
terminals.
This vehicle is equipped with five-vane rotary com­
pressor.
The
compressor has vanes built into a rotor which is
mounted on a shaft.
When the shaft rotates, the vanes built into the
cylinder block assembly are opened by centrifugal
force.
This changes the volume of the space formed by the
rotor and cylinder, resulting in the intake and
compression of the refrigerant gas. The discharge
valve and the
valve stopper, which protects the
discharge valve, are
built into the cylinder block
assembly. There is no suction valve but a shaft seal
is
installed between the shaft and head; a trigger
valve, which applies back pressure to the vanes, is
installed in the cylinder block and a refrigerant gas
temperature sensor is installed in the front head.
The specified
quantity of compressor oil is contained
in
the compressor to lubricate the various parts
using
the refrigerant gas discharge pressure.
The thermo sensor is installed to the front head of
the compressor to protect it by stopping its
operation when the refrigerant gas is insufficient or
when the temperature get abnormally high.
•OFF ..... 160 ±soc (320.0 ± 9.0°F)
•ON ..... 135 ±soc (275.0 ± 9.0°F)
The oil used in the HFC-134a system compressor
differs from that used in R-12 systems.
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 specified
amount of the compressor oil is
150cc (5.0 fl.oz.).

1 D-2 COMPRESSOR OVERHAUL
Fig. 1 D-1
DIAGNOSIS
ITEM PROBLEM POSSIBLE CAUSES CORRECTION
1
Noise from compressor 1. Defective rotor Replace compressor
2. Defective shaft Replace compressor
2 Noise
from magnetic 1. Defective bearing Replace magnetic clutch
clutch
face 2. Defective clutch Replace magnetic clutch
3. Clearance
between drive plate and pulley Replace magnetic clutch
not standard or adjust
the clearance
3
Insufficient cooling 1. Defective gasket Replace
compressor
2. Defective rotor Replace compressor
3. Defective trigger valve Replace compressor
4 Not rotating 1. Defective rotor Replace compressor
2. Defective shaft Replace compressor
3. Rotating parts seized due to insufficient oil Replace compressor
5 Oil and/or gas leakage 1. Defective seal Replace compressor
2. Defective 0-ring Replace
•