sensor ISUZU TROOPER 1998 Service Repair Manual

ABBREVIATIONS CHARTS
LIST OF AUTOMOTIVE ABBREVIATIONS WHICH MAY BE USED IN THIS MANUAL
A Ð Ampere(s)
ABS Ð Antilock Brake System
A/C Ð Air Conditioning
ACCEL Ð Accelerator
ACC Ð Accessary
Adj Ð Adjust
A/F Ð Air Fuel Ratio
AIR Ð Air Injection Reaction System
ALDL Ð Assembly Line Diagnostic Link
Alt Ð Altitude
AMP Ð Ampere(s)
ANT Ð Antenna
APS Ð Absolute Pressure Sensor
ASM Ð Assembly
A/T Ð Automatic Transmission/Transaxle
ATDC Ð After Top Dead Center
Auth Ð Authority
Auto Ð Automatic
BARO Ð Barometic
Bat Ð Battery
Bat+ Ð Battery Positive Terminal
Bbl Ð Barrel
BCM Ð Body Control Module
BHP Ð Brake Horsepower
BP Ð Back Pressure
BTDC Ð Before Top Dead Center
¡C ÐDegrees Celsius
Cat. Conv. Ð Catalytic Converter
cc Ð Cubic Centimeter
CCC Ð Computer Command Control
CCOT Ð Cycling Clutch Orifice Tube
CCP Ð Controlled Canister Purge
CID Ð Cubic Inch Displacement
CL Ð Closed Loop
CLCC Ð Closed Loop Carburetor Control
CO Ð Carbon Monoxide
Coax Ð Coaxial
Conn Ð Connector
Conv Ð Converter
CP Ð Canister Purge
CPS Ð Central Power Supply
Crank Ð Crankshaft
CTS Ð Coolant Temperature Sensor
Cu.In. Ð Cubic Inch
CV Ð Constant Velocity
Cyl Ð Cylinder(s)
C
3I Ð Computer Controlled Coil Ignition
DBM Ð Dual Bed Monolith
Diff Ð Differential
DIS Ð Direct Ignition System
Dist ÐDistributor
DOHC Ð Double Overhead Camshaft
DVM Ð Digital Voltmeter (10 meg.)
DVOM Ð Digital Volt Ohmmeter
DVDV Ð Differential Vacuum Delay Valve
EAC ÐElectric Air Control
EAS Ð Electric Air Switching
EBCM Ð Electronic Brake Control Module
ECC Ð Electronic Climate Control
ECM Ð Electronic Control Module
ECU Ð Electronic Control Unit
Ð Engine Calibration Unit (PROM)
EECS Ð Evaporative Emission Control System
EFE Ð Early Fuel Evaporation
EFI Ð Electronic Fuel Injection
EGR Ð Exhaust Gas Recirculation
EGR/TVS Ð Exhaust Gas Recirculation/Thermostatic
Vacuum Switch
ELC Ð Electronic Level Control
ESC Ð Electronic Spark Control
EST Ð Electronic Spark Control
ETR Ð Electronically Tuned Receiver
EVRV Ð Electronic Vacuum Regulator Valve (EGR)
Exh Ð Exhaust
¡F Ð Degrees Fahrenheit
FF Ð Front Drive Front Engine
FL Ð Fusible Link
FLW Ð Fusible Link Wire
FRT ÐFront
FWD Ð Front Wheel Drive
4WD Ð Four Wheel Drive
4x4 Ð Four Wheel Drive
4 A/T Ð Four Speed Automatic Transmission/Transaxle
Gal Ð Gallon
Gen Ð Generator
Gov Ð Governor
g Ð Gram
Harn Ð Harness
HC Ð Hydrocarbons
HD ÐHeavy Duty
HEI Ð High Energy Ignition
Hg Ð Mercury
HiAlt Ð High Altitude
HVAC Ð Heater-Vent-Air Conditioning
IAC Ð Idle Air Control
IC Ð Integrated Circuit
ID Ð Identification
Ð Inside Diameter
IDI Ð Integrated Direct Ignition
IGN Ð Ignition
ILC Ð Idle Load Compensator
INJ ÐInjection
IP Ð Instrument Panel
IPC Ð Instrument Panel Cluster
INT Ð Intake
J/B Ð Junction Block
km Ð Kilometers
km/h Ð Kilometer per Hour
kPa Ð KiloPascals
KV Ð Kilovolts (thousands of volts)
KW Ð Kilowatts
0AÐ12 GENERAL INFORMATION

SAE Ð Society of Automotive Engineers
Sec Ð Secondary
SFI Ð Sequential-port Fuel Injection
SI Ð System International
SIR Ð Supplemental Inflatable Restraint System
SOHC Ð Single Overhead Camshaft
Sol Ð Solenoid
SPEC Ð Specification
Speedo Ð Speedometer
SRS Ð Supplemental Restraint System
ST Ð Start
Sw Ð Switch
SWB Ð Short Wheel Base
SYN Ð Synchronize
TAC Ð Thermostatic Air Cleaner
Tach Ð Tachometer
TBI Ð Throttle Body Injection
TCC Ð Transmission/Transaxle Converter Clutch
TCM Ð Transmission/Transaxle Control Module
TDC Ð Top Dead Center
Term Ð Terminal
TEMP Ð Temperature
TPS Ð Throttle Position Sensor
TRANS Ð Transmission/Transaxle
TURBO Ð Turbocharger
TV Ð Throttle Valve
TVRS Ð Television & Radio Suppression
TVS Ð Thermal Vacuum Switch
3 A/T Ð Three Speed Automatic Transmission/
Transaxle
2WD Ð Two Wheel Drive
4x2 Ð Two wheel Drive
U-joint Ð Universal Joint
V Ð Volt(s)
VAC Ð Vacuum
VIN Ð Vehicle Identification Number
VRRRE Ð Vehicle Refrigerant Recovery and Recycling
Equipment
V-ref Ð ECM Reference Voltage
VRV Ð Vacuum Reducer Valve
VSS Ð Vehicle Speed Sensor
VSV Ð Vacuum Switching Valve
V-6 Ð Six Cylinder ÒVÓ Engine
V-8 Ð Eight Cylinder ÒVÓ Engine
W Ð Watt(s)
w/ Ð With
w/b Ð Wheel Base
w/o Ð Without
WOT Ð Wide Open ThrottleL Ð Liter
lbáft Ð Foot Pounds
lbáin Ð Inch Pounds
LF Ð Left Front
LH Ð Left Hand
LR Ð Left Rear
LS Ð Left Side
LWB Ð Long Wheel Base
L-4 Ð In-line Four Cylinder Engine
MAF Ð Mass Air Flow
MAN Ð Manual
MAP Ð Manifold Absolute Pressure
MAT Ð Manifold Air Temperature
MEM-CAL Ð Memory and Calibration Unit
Max Ð Maximum
M/C Ð Mixture Control
Min Ð Minimum
mm Ð Millimeter
MPFI Ð Multi-Port Fuel Injection
MPG Ð Miles per Gallon
MPH Ð Miles per Hour
M/T Ð Manual Transmission/Transaxle
MV Ð Millivolt
NA Ð Natural Aspirated
NC Ð Normally Closed
Nám Ð Newton Meters
NO Ð Normally Open
NOx Ð Nitrogen, Oxides of
OD Ð Outside Diameter
O/D Ð Over Drive
OHC Ð Overhead Camshaft
OL Ð Open Loop
O
2Ð Oxygen
PAIR Ð Pulse Air Injection Reactor System
P/B Ð Power Brakes
PCV Ð Positive Crankcase Ventilation
PFI Ð Port Fuel Injection
PRESS Ð Pressure
PROM Ð Programmable Read Only Memory
P/N Ð Park/Neutral
P/S Ð Power Steering
PSI Ð Pounds per Square Inch
Pt. Ð Pint
Pri Ð Primary
PWM Ð Pulse Width Modulated
Qt Ð Quart
REF Ð Reference
RF Ð Right Front
RFI Ð Radio Frequency Interference
RH Ð Right Hand
RPM Ð Revolutions per Minute
RPO Ð Regular Production Option
RR Ð Right Rear
RS Ð Right Side
RTV Ð Room Temperature Vulcanizing
RVB Ð Rear Vacuum Brake
RVR Ð Response Vacuum Reducer
RWAL Ð Rear Wheel Antilock Brake
RWD - Rear Wheel Drive
GENERAL INFORMATION 0AÐ13

0BÐ2 MAINTENANCE AND LUBRICATION
MAINTENANCE SCHEDULE
GASOLINE ENGINE MODELI: Inspect and correct or replace as necessary A: Adjust
R: Replace or change T: Tighten to specified torque L: Lubricate
SERVICE INTERVAL: x 1,000 km
(Use odometer reading x 1,000 miles
or months whichever comes first) or months5
3
610
6
1215
9
1820
12
2425
15
3030
18
3635
21
4240
24
4845
27
5450
30
6055
33
6660
36
7265
39
7870
42
8475
45
9080
48
9685
51
10290
54
10895
57
114100
60
120
GASOLINE ENGINE
* Engine oil
* Engine oil filter
Oil leakage and contamination
* Timing belt
Spark plugs (For leaded fuel use)
Spark plugs (For unleaded fuel use)
Exhaust system
Radiator coolant concentration
Cooling system for water leakage
All hoses and pipes in engine compartment
for clog or damage
Fuel filter
Fuel leakage
Fuel tank
* Air cleaner element
Pre air cleaner
Engine drive belt
Valve clearance
O
2 Sensor (For leaded fuel use)
O
2 Sensor (For unleaded fuel use)-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
R
R
-
I
I
I
I
-
I
I
I
I
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
R
I
-
I
I
I
I
R
I
I
I
I
I
--
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
R
-
-
-
-
-
-
-
-
-
-
-R
R
I
-
I
I
I
I
-
I
I
R
I
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
R-
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
R
I
-
I
I
I
I
R
I
I
I
I
I
--
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
R
I
-
I
I
I
I
-
I
I
I
I
-
--
-
-
R
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
R
I
-
I
I
I
I
R
I
I
R
I
I
--
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
R
(Replace every 165,000 km or 100,000 miles)
(Replace every 165,000 km or 100,000 miles)
(Check and adjust if necessary every 100,000 km or 60,000 miles)
(Replace every 150,000 km or 90,000 miles)
CLUTCH
Clutch fluid
Clutch pedal travel and free play
TRANSMISSION OR TRANSMISSION WITH
TRANSFER CASE
* Manual transmission with transfer case oil
* Automatic transmission fluid leakage
*
(1)Automatic transmission fluid
* Transfer case oil
PROPELLER SHAFT
Loose connections
*
Universal joints and splines for wear
Universal joints and sliding sleeve (front and rear)
FRONT AND REAR AXLE
* Differential gear oil (Front and rear)
Shift on the fly system gear oil
Front axle shaft rubber boot for damage
Axle case for distortion or damage
Axle shafts for distortion or damage-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
R
I
-
R
I
I
L
R
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
-
I
I
I
L
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
R
I
-
R
I
I
L
R
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
-
I
I
I
L
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
R
I
-
R
I
I
L
R
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
-
I
I
I
L
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
I
-
I
I
-
-
-
I
-
-
-
-
ATATAT
STEERING
* Power steering fluid
Oil leakage
* Steering system for looseness or damage
Power steering hose
Steering wheel play
Steering function
Right and left turning radius
Wheel alignment
Joint ball for oil leakage or damage
Joint ball rubber boot for damage
SERVICE BRAKES
Brake fluid
Brake system for fluid leakage
Brake function
* Disc brake pads and discs wear
Brake pedal travel and free play
Pipes and hoses for loose connections or damage
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
I
I
-
-
I
I
I
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
I
I
I
I
I
-
-
I
I
R
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-I
I
I
R
I
I
-
-
I
I
I
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-R
I
I
I
I
I
I
I
I
I
R
I
I
I
I
I-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
(1): Adjust or change automatic transmission fluid.
*Marks: Under severe driving conditions, additional maintenance is required.
Refer to “Maintenance schedule under severe driving conditions”.

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
SERVICE INFORMATION 00 Ð 25
Reduced or no air flow through
the condenser
No bubbles in sight glass when
condenser is cooled by water
(Insufficient cooling)
After stopping air conditioning,
pressure drops approx. 196 kPa
(28 PSI) quickly
Insufficient cooling and excessive
bubbles in the sight glass
Low pressure gauge indicates
vacuum
Frost or dew on refrigerant line
before and after receiver/ drier or
expansion valve, and low pres-
sure gauge indicates vacuum
After turning off air conditioning,
high and low pressure gauge
balanced quickly
Low pressure gauge is lowered
after condenser is cooled by
water
Low pressure hose temperature
around the compressor refriger-
ant line connector is lower than
around evaporator
After turning off air conditioning,
high and low pressure gauge is
balanced quickly
Air conditioning turns off before
passenger compartment is suffi-
ciently cool·Condenser clogged or dirty
·Radiator (condenser) fan
does not operate properly
·Excessive refrigerant in
system
·Air in system
·Insufficient refrigerant in
system
·Clogged or defective expan-
sion valve
·Restriction caused by debris
or moisture in receiver/drier
·Compressor seal defective
·Poor compression due to
defective compressor gasket
·Excessive refrigerant in
system
·Unsatisfactory valve opera-
tion due to defective temper-
ature sensor of expansion
valve
·Expansion valve opens too
long
·Compressor gasket is defec-
tive
·Electronic thermostat defec-
tive·Clean
·Check cooling fan
operation
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Evacuate and
charge refrigerant
system
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Check system for
restriction and
replace
receiver/drier
·Replace or repair
compressor
·Discharge and
recover refrigerant
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Replace
·Check the electronic
thermostat and
replace as neces-
saryDischarge
(High) pres-
sure gauge
abnormally
high
Discharge
(High) pres-
sure gauge
abnormally
low
Suction
(Low) pres-
sure gauge
abnormally
high
* For the charging and discharging operations in the table above, refer to ÒRECOVERY, RECYCLING,
EVACUATION AND CHARGINGÓ in this section.

RESULT SYMPTOM TROUBLE CAUSE CORRECTION
Suction
(Low) pres-
sure abnor-
mally low
Suction
(Low) and
Discharge
(High) pres-
sure abnor-
mally high
Suction
(Low) and
Discharge
(High) pres-
sure abnor-
mally low
00 Ð 26 SERVICE INFORMATION
·Check sight
glass.(See ÒReading
Sight GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Replace the expan-
sion valve
·Replace the receiv-
er/drier
·Replace the expan-
sion valve
·Check electronic
thermostat and
replace as necessary
·Replace refrigerant
line
·Check sight
glass.(See ÒReading
Sight GlassÓ)
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount
·Clean
·Check cooling fan
operation
·Evacuate and charge
refrigerant
·Check sight glass.
(See ÒReading Sight
GlassÓ)
·Check for leaks
·Discharge and
recover refrigerant.
Recharge to speci-
fied amount·Insufficient refrigerant
·Expansion valve clogged
·Receiver/drier clogged
·The temperature sensor of
the expansion valve is defec-
tive, and the valve cannot
regulate the correct flow of
the refrigerant
·Frozen evaporator core fins
·Clogged or blocked refriger-
ant line
·Excessive refrigerant in
system
·Condenser clogged
·Radiator (condenser) fan
does not rotate properly
·Air in system
·Insufficient refrigerant in
systemCondenser is not hot and exces-
sive bubble in sight glass
Frost on the expansion valve inlet
line
A distinct difference in tempera-
ture between the inlet and outlet
refrigerant lines of the
receiver/drier
Expansion valve outlet refrigerant
line is not cold and low-pressure
gauge indicates vacuum
Discharge temperature is low and
air flow from vents is restricted
Low-pressure gauge reading is
low, or a vacuum reading may be
shown
No bubbles in sight glass after
condenser is cooled by water
(Insufficient cooling)
Reduce air flow through con-
denser
Suction (Low) pressure hose is
not cold
Insufficient cooling and excessive
bubbles in the sight glass

1B Ð 2 AIR CONDITIONING
Full Automatic Air Conditioning System....................................1BÐ 60
General Description.....................................................1BÐ 60
Full Automatic Air Conditioner Part Configuration.........................1BÐ 60
Circuit Diagram......................................................1BÐ 62
Function and Features.................................................1BÐ 74
Full Automatic Air Conditioner Block Diagram.............................1BÐ 75
Air Conditioning Parts.................................................1BÐ 76
Control Panel Layout..................................................1BÐ 80
Air Control Functions.................................................1BÐ 81
Operation and Function of Control Panel Switches.........................1BÐ 82
Overview of Construction, Movement and Control of Major Parts of Full Automatic
Air Conditioner System................................................1BÐ 84
Overview of Automatic Control of Full Automatic Air Conditioner............1BÐ 88
Troubleshooting........................................................1BÐ 92
Troubleshooting, Its Overview and Procedures............................1BÐ 92
Performance and Movement Checklist for Automatic Air Conditioner Related
Parts...............................................................1BÐ 95
Troubleshooting with Self-Diagnosis Function............................1BÐ 97
Inspection by Failed Location.............................................1BÐ100
Inspection of the Sensors..............................................1BÐ100
Inspection of the Intake Actuator System.................................1BÐ104
Inspection of the Mix Actuator System...................................1BÐ107
Inspection of the Mode Actuator System.................................1BÐ110
Inspection of the Fan Motor System.....................................1BÐ113
Inspection of the Magnet Clutch System.................................1BÐ118
Inspection of the Air Conditioner Room Temperature Setup System..........1BÐ123
Individual Inspection..................................................1BÐ124
On-Vehicle Service......................................................1BÐ126
Power Transistor.....................................................1BÐ126
Automatic Air Conditioner Control Unit..................................1BÐ126
In Car Sensor........................................................1BÐ127
Ambient Sensor......................................................1BÐ127
Sun Sensor..........................................................1BÐ128
Electronic Thermostat.................................................1BÐ128
Mode Actuator.......................................................1BÐ129
Mix Actuator.........................................................1BÐ129
Intake Actuator......................................................1BÐ130

AIR CONDITIONING 1B Ð 3
AIR CONDITIONING REFRIGERANT CYCLE CONSTRUCTION




 

 













 

 
 
 
 

 
 


 












 

 
 
 
 
 
 





1514
11
12
13
1610
177
34
5
2
18
96
13 Side vent
Lap ventOutside air
EngineSide vent
Cooling air
High pressure, high temperature gas
High pressure, high temperature
mixture of gas and liquid
Low pressure, low temperature
mixture of liquid and gas
Low pressure, low temperature gas High pressure, medium temperature liquidSide defrost Side defrostDefrost Center vent
GENERAL DESCRIPTION
1. Compressor
2. Magnetic clutch
3. Receiver/Drier
4. Dual pressure switch
5. Condenser
6. Evaporator assembly
7. Expansion valve
8. Temperature sensor
9. Evaporator core10. Blower motor
11. Heater unit
12. Heater core
13. Temp. control door (Air mix door)
14. Mode (DEF) control door
15. Mode (VENT) control door
16. Mode (HEAT) control door
17. Electronic thermostat

1B Ð 4 AIR CONDITIONING
The refrigeration cycle includes the following four
processes as the refrigerant changes repeatedly
from liquid to gas and back to liquid while
circulating.
EVAPORATION
The refrigerant is changed from a liquid to a gas
inside the evaporator. The refrigerant mist that
enters the evaporator vaporizes readily. The liquid
refrigerant removes the required quantity of heat
(latent heat of vaporization) from the air around the
evaporator 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
temperatures close to 0¡C (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.
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
The 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 A/C system.
6VD1/6VE1 engine on RHD model is equipped with
an invariable capacity five-vane rotary compressor
(DKV-14D Type).
The compressor sucks and compresses refrigerant
by the rotation of the vane installed to the shaft,
and always discharges a fixed amount of refrigerant
independent of the load of refrigerant.
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 ±5¡C (320.0 ±41¡F)
·ON ........ 135 ±5¡C (275.0 ±41¡F)
Diesel Engine models and 6VD1/6VE1 engine on
LHD model are equipped with a swash plate type
compressor
Swash plate compressors have a swash (slanted)
plate mounted on the shaft. When the shaft turns,
the rotation of the swash plate is converted to
reciprocating piston motion which sucks in and
compresses the refrigerant gas.
Shaft seal (Lip type) is installed between the valve
plate and shaft & cylinder head to prevent
refrigerant gas leaks. A specified amount of
compressor oil is contained in the oil pan.
This oil is supplied to the cylinders, bearings, etc.,
by an oil pump which is connected to the swash
plate shaft.

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