1995 ISUZU TROOPER Workshop Manual

AIR CONDITIONING 1 B -11
RESULT CHECK POINT/SYMPTOM TROUBLE CAUSE CORRECTION
Discharge
(High 1. Condenser or cooling 1. Condenser clogged or 1. Clean the condenser
Gauge) Pressure fan. dirty. fins.
Abnormally Cooling fan does not Check cooling fan
High operate properly. operation.
2. Insufficient cooling. 2. Excessive refrigerant 2. • Discharge and
in system. recover
refrigerant.
Recharge
to
specified amount.
3. High pressure gauge 3. Air in system. 3. Evacuate and charge
drop (After stopping refrigerant system.
A/C, pressure
drops
approx. 196 kPa/28 psi
quickly).
Discharge (High 1. Insufficient cooling. 1. Insufficient refrigerant 1 .• Check for leaks.
Gauge)
Pressure in system. • Discharge and
Abnormally Low recover refrigerant.
Recharge
to
specified amount.
2. Low pressure gauge 2. Clogged or defective 2. Replace expansion
indicates vacuum.
expansion
valve. valve.
3. Frost or dew on 3. Restriction caused by 3. Check system for
refrigerant line before
debris or moisture in restriction
and replace
and after receiver/drier
receiver/drier. receiver/drier.
or expansion valve,
and low pressure
gauge indicates
vacuum.
4. High and low pressure 4. • Compressor seal 4. Repair or replace the
gauge balanced defective. compressor.
quickly (After turned • Poor
compression
off A/C). due to defective
compressor gasket.
A/C-Air Conditioning

1 B -12 AIR CONDITIONING
RESULT CHECK POINT /SYMPTOM
TROUBLE CAUSE CORRECTION
Suction (low 1. Low pressure
gauge 1. Excessive refrigerant 1. Discharge and recover
Gauge) Pressure (Low pressure gauge
in system. refrigerant.
Recharge
Abnormally is lowered after to specified amount.
High condenser is cooled
by water).
2. Low pressure hose 2. • Unsatisfactory valve 2. Replace the expansion
temperature (Low operation due to valve.
pressure hose
defective
temperature around
temperature sensor
the compressor of expansion valve.
refrigerant line
• Expansion valve
connector is lower than opens too long.
around evaporator).
3. High and low pressure 3. Compressor gasket is 3. Repair or replace the
gauge balanced defective. compressor.
quickly (After turned
off A/C).
Suction (low 1. Insufficient cooling. 1. Insufficient refrigerant 1 .• Check for leaks.
Gauge) Pressure in system. • Discharge and
Abnormally Low recover refrigerant.
Recharge
to
specified amount.
2. Frost on the expansion 2. Expansion valve 2. Replace the expansion
valve inlet line.
clogged. valve.
3. Receiver/drier inlet and 3. Receiver/Drier clogged 3. Replace the
outlet refrigerant line receiver/drier.
temperature (A distinct
difference in
temperature
develops).
4. Expansion valve outlet 4. Expansion valve 4. Replace the expansion
refrigerant line (Not temperature sensor valve.
cold
and low pressure defective.
gauge indicates
vacuum).
5. When the refrigerant 5. Clogged or blocked 5. Replace refrigerant
line is clogged or refrigerant line. line.
blocked,
the low
pressure gauge
reading
will decrease,
or a vacuum reading
may be shown.
6. Evaporator core is 6. Thermo switch 6. Replace thermo
frozen.
defective. switch.
A/C-Air Conditioning
..

AIR CONDITIONING 1 B -13
RESULT CHECK POINT /SYMPTOM
TROUBLE CAUSE CORRECTION
Suction (low 1. Insufficient cooling. 1. Excessive refrigerant 1. Discharge
and recover
Gauge) and in system. refrigerant, then
Discharge
(High Recharge to specified
Gauge) Pressure 2. Condenser. 2. Condenser clogged or amount.
Abnormally dirty. 2. Clean the condenser
High 3. Suction (Low) pressure 3. Air in system. fin.
hose (Not
cold). 3. Evacuate and charge
refrigerant.
Suction (Low 1. Insufficient cooling. Insufficient refrigerant in • Check for leaks.
Gauge) and system. • Discharge and recover
Discharge (High refrigerant. Recharge to
Gauge) Pressure specified amount.
Abnormally Low
A/C-Air Conditioning

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