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Quick Checking of Refrigerant Charge
The following procedure can be used for quickly checking whether
the A/C system has a proper charge of refrigerant or not.
Run engine at fast idle, and operate A/C at its maximum cooling
capacity for a few minutes. Then, look at the sight glass (1) on
receiver / dryer (2) and compare what is observed with the symp-
toms listed in below.
CHECKING REFRIGERANT CHARGE
3. Bubbles
Symptom Charge of refrigerant condition Correction
Bubbles observed in sight glass Insufficient charge of refrigerant in
systemCheck system for leaks with a
leak tester.
No bubbles observed in sight glass No or insufficient charge of refrig-
erant in systemRefer to the items 3 and 4.
No temperature difference between
compressor inlet and outletEmpty or nearly empty system Evacuate and charge system and
then check it for leaks with a leak
tester.
Noticeable temperature difference
between compressor inlet and outletProper or too much charge of
refrigerant in systemRefer to the items 5 and 6.
When A/C is turned OFF, refrigerant in
sight glass clears immediately and
remains clearToo much charge of refrigerant in
systemDischarge excess refrigerant in
order to obtain a specified charge.
When A/C is turned OFF, refrigerant in
sight glass once produces bubbles and
then clearsProper charge of refrigerant in
systemNo correction needed because
charge of refrigerant is normal.
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Performance Diagnosis
1) Confirm that vehicle and environmental conditions are as fol-
lows.
Vehicle is not exposed to direct sun.
Ambient temperature is within 15 – 35 °C (59 – 95 °F).
2) Make sure that high pressure valve (1) and low pressure
valve (2) of manifold gauge set (3) are firmly closed.
3) Connect high pressure charging hose (4) to high pressure
service valve (5), and connect low pressure charging hose
(6) to low pressure service valve (7).
4) Bleed the air in charging hoses (4), (6) by loosening their
respective nuts on manifold gauge set (3), utilizing the refrig-
erant pressure. When a hissing sound is heard, immediately
tighten nut.
5) Warm up engine to normal operating temperature (engine
coolant temperature at 80 – 90 °C (176 – 194 °F)) and keep
it at specified idle speed. (Radiator cooling fan should not be
working when checking pressure and temperature.)
6) Turn A/C switch ON, and set blower switch at “HI” (3rd posi-
tion), temperature knob at “COOL” air outlet control knob at
“FACE” and fresh / circulation control knob at “CIRCULA-
TION”. (Confirm that A/C compressor and radiator / con-
denser cooling fan are working.)
Keep all windows, doors and engine food open.
Performance diagnosis condition
7) With dry bulb thermometer (1) inserted into center duct air
outlet and another one set near evaporator air inlet, read
temperature indicated on each thermometer. CAUTION:
Do not interchange high and low pressure charging
hoses by mistake.
Ambient temperature 15 – 35 °C (59 – 95 °F)
Engine rpm Keep to 1,500 rpm.
Blower fan motor switch “H” (3rd position)
Temperature control “Cool”
Air outlet control “Face”
Vehicle doors All open
Air inlet door position Recirculation
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Performance diagnosis table
HIGH PRESSURE GAUGE
LOW PRESSURE GAUGE
NOTE:
If ambient temperature is approximately 30 °C (86 °F), it is possible to diagnose A/C system in detail
referring to “Detail Diagnosis Table (Ambient Temperature At 30 °C (86 °F))” under “Performance
Diagnosis” in this section.
Condition Possible Cause Correction
Pressure in higher
than acceptable range
(“A” area)Refrigerant overcharged Recharge
Expansion valve frozen or clogged Check expansion valve
Clogged refrigerant passage of high side Clean or replace
Condenser cooling fan malfunction (Insufficient
cooling of condenser)Check condenser cooling fan
Dirty or bent condenser fins (Insufficient cooling
of condenser)Clean or repair
Compressor malfunction (Insufficient oil etc.) Check compressor
Engine overheat Check engine cooling system refer-
ring to Section 6B.
Pressure is lower than
acceptable range
(“B” area)Insufficient refrigerant (Insufficient charge or
leakage)Check for leakage, repair if neces-
sary and recharge
Expansion valve malfunction (valve opens too
wide)Check expansion valve
Compressor malfunction (Insufficient compres-
sion)Check compressor
Condition Possible Cause Correction
Pressure is higher
than acceptable range
(“C” area)Expansion valve malfunction (valve opens too
wide)Check expansion valve
Compressor malfunction (Insufficient compres-
sion)Check compressor
Pressure is lower than
acceptable range
(“D” area)Insufficient refrigerant (Insufficient charge or
leakage)Check for leakage, repair if neces-
sary and recharge
Expansion valve malfunction (valve opens too
narrow)Check expansion valve
Clogged refrigerant passage (crashed pipe) Repair or replace
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CROSSING POINT OF CENTER VENTILATION LOUVER TEMPERATURE AND RECIRCULATION AIR
INLET TEMPERATURE
Detail diagnosis table (Ambient temperature at 30°C (86°F))
Condition Possible Cause Correction
Crossing point is
higher than accept-
able range
(“E” area)Insufficient or excessive charge of refrigerant Check refrigerant pressure
Dirty or bent A/C evaporator fins Clean or repair
Air leakage from cooling (heater) unit or air duct Repair or replace
Malfunctioning, switch over function of door in
cooling (heater) unitRepair or replace
Compressor malfunction Check compressor
Crossing point is
lower than acceptable
range
(“F” area)Insufficient air volume from center duct (Heater
blower malfunction)Check blower motor and fan
Compressor malfunction Check compressor
Condition
Possible Cause Correction MANIFOLD
GAUGEMPa
(kg/cm
2)
(psi)Detail
Lo Hi
0.23 – 0.35
(2.3 – 3.5)
(33 – 50)1.4 – 1.75
(14 – 17.5)
(200 – 249)Normal condition
––
Negative
pressure0.5 – 0.6
(5 – 6)
(71.2 – 85.3)The low pressure side
reads a negative pres-
sure, and the high pres-
sure side reads an
extremely low pressure.
Presence of frost
around tubing to and
from receiver / dryer
and expansion valve.Dust particles or water
droplets are either stuck
or frozen inside expan-
sion valve, preventing the
refrigerant from flowing.Clean expansion valve.
Replace it if it cannot be
cleaned.
Replace receiver / dryer.
Evacuate the A/C sys-
tem and recharge with
fresh refrigerant.
Normal :
0.23 – 0.35
(2.3 – 3.5)
(33 – 50)
↑
↑ ↑ ↑ ↓
↓↓ ↓
Abnormal :
Negative
pressureNormal :
1.4 – 1.75
(14 – 17.5)
(200 – 249)
↑
↑ ↑ ↑ ↓
↓↓ ↓
Abnormal :
0.69 – 0.98
(7 – 10)
(100 – 142)During A/C operation,
the low pressure side
sometimes indicates
negative pressure, and
sometimes normal
pressure. Also high
pressure side reading
fluctuates between the
abnormal and normal
pressure.Expansion valve is frozen
due to moisture in the
system, and temporarily
shuts off the refrigeration
cycle.Replace expansion valve.
Replace receiver / dryer.
Evacuate A/C system
and recharge with fresh
refrigerant.
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0.05 – 0.15
(0.5 – 1.5)
(4.2 – 21.3)
0.69 – 0.98
(7 – 10)
(100 – 142)Both low and high pres-
sure sides indicate low
readings.
Continuous air bub-
bles are visible through
sight glass.
Output air is slightly
cold.Insufficient refrigerant in
system.
(Refrigerant leaking)Using leak detector,
check for leaks and repair
as necessary.
Recharge refrigerant to a
specified amount.
If the pressure reading is
almost 0 when the mani-
fold gauges are attached,
check for any leaks,
repair them, and evacu-
ate the system.
0.4 – 0.6
(4 – 6)
(56.9 – 85.3)Pressure on low pres-
sure side is high.
Pressure on high pres-
sure side is low.
Both pressure becom-
ing equal right after A/C
is turned OFF.Internal leak in compres-
sor.Inspect compressor and
repair or replace as nec-
essary.
0.35 – 0.45
(3.5 – 4.5)
(50 – 64)
1.96 – 2.45
(20 – 25)
(285 – 355)Pressure on both low
and high pressure
sides is high.
Air bubbles are not visi-
ble even when engine
rpm is lowered.Overcharged A/C sys-
tem.Adjust refrigerant to
specified amount.
Faulty condenser cooling
operation.Clean condenser.
Faulty condenser cooling
fan operation.Inspect and repair con-
denser cooling fan.
Pressure on both low
and high pressure
sides is high.
Low pressure side tub-
ing is not cold when
touched.
Air bubbles are visible
through sight glass.Presence of air in A/C
system.
(Improperly evacuated)Replace receiver / dryer.
Inspect quantity of com-
pressor oil and presence
of contaminants in oil.
Evacuate system and
recharge with fresh
refrigerant.
0.45 – 0.55
(4.5 – 5.5)
(64 – 78)Pressure on both low
and high pressure
sides is high.
Large amount of frost
or dew on the low pres-
sure side tubing.Faulty expansion valve.
Refrigerant flow is not
regulated properly.Replace expansion valve. Condition
Possible Cause Correction MANIFOLD
GAUGEMPa
(kg/cm
2)
(psi)Detail
Lo Hi
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Compressor Drive Belt
INSPECTION
Check belt for wear and cracks, and replace as required.
Check belt tension by measuring how much it deflects when
pushed at intermediate point between compressor pulley (1)
and crankshaft pulley (2) with about 100 N (10 kg, 22 lb)
force.
If belt tension is out of above specification, adjust belt ten-
sion according to the following procedures.
Deflection of compressor drive belt
“a” : 6 – 9 mm (0.24 – 0.35 in.)
ADJUSTMENT
For Vehicle With P/S
1) Loosen tension pulley bolts (3) and set hexagon wrench (4)
to hexagon hole.
2) Turn tension pulley (5) counterclockwise by hexagon wrench
in order to obtain above specified tension.
3) Tighten tension pulley bolts (3) to specified torque.
Tightening torque
Tension pulley bolts
(a) : 25N·m (2.5 kg-m, 18.0 lb-ft)
For Vehicle Without P/S
1) Loosen tension pulley tightening nut (6).
2) Adjust belt tension by tighten or loosen tension pulley adjust-
ing bolt (7) in order to obtain above specified tension.
3) Tighten tension pulley tightening nut (6).
[A] : Vehicle with P/S
[B] : Vehicle without P/S
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Terminal arrangement of ECM coupler (Viewed from harness side)
1. Blower fan motor 8. Compressor [A]: To “A/C” fuse (25A) in main fuse box
2. Dual pressure switch 9. Thermal switch [B]: To “HEATER” fuse (20A) in circuit fuse box
3. A/C switch 10. Main relay [C]: To “FI” fuse (15A) in main fuse box
4. A/C evaporator thermistor 11. Engine earth [D]: 4WD model
5. ECT sensor 12. Blower fan motor switch [E]: 2WD model
6. Condenser cooling fan motor relay 13. 4WD controller
7. Condenser cooling fan motor 14. ECM
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ECM VOLTAGE VALUES TABLE FOR RELATION OF A/C CONTROL
Terminal Wire CircuitMeasurement
groundNormal value Condition
E18-1 PCompressor
magnet clutch
outputGround to
engine (Fig B)10 – 14 voltBlower fan motor switch and A/C
switch ON with engine running
0 – 1 voltsExcept the above-mentioned condi-
tion with engine running
E18-5 Bl/BMain power sup-
ply for ECMGround to
engine (Fig B)10 – 14 voltsIgnition switch ON with engine
stopped
E18-6 Bl/BMain power sup-
ply for ECMGround to
engine (Fig B)10 – 14 voltsIgnition switch ON with engine
stopped
E18-10 Bl Main relay driveGround to
engine (Fig B)0.5 – 1.2 voltIgnition switch ON with engine
stopped
0 volts Ignition switch OFF
E18-16 G/W A/C switch inputGround to
engine (Fig B)12 – 15 voltsBlower fan motor switch or A/C switch
OFF with engine running
0 – 1 voltBlower fan motor switch and A/C
switch ON with engine running
12 – 15 voltsWithin several seconds after operate
transfer lever between 2WD and 4WD
with above condition
E18-18 P/BCompressor
cooling fan relay
outputGround to
engine (Fig B)0 – 1 voltBlower fan motor switch and A/C
switch ON or engine coolant tempera-
ture at more than 110 °C (230 °F) with
engine running.
12 – 15 voltsExcept the above-mentioned condi-
tion with engine running
E18-20 B/BlSensor ground
for A/C evapora-
torGround to
body (Fig A)–0.5 – 0 volt Engine running
E18-24 Bl/YBlower fan
speed inputGround to
engine (Fig B)0 – 1 voltBlower fan motor switch 2nd or 3rd
with engine running
4 – 7 voltsBlower fan motor switch 1st with
engine running
12 – 15 voltsBlower fan motor switch and A/C
switch OFF with engine running
E19-1 BMain ground for
ECMGround to
engine (Fig A)–0.5 – 1 volt Engine running
E19-2 B/RECM ground for
power circuitGround to
engine (Fig A)–0.5 – 1 volt Engine running
E19-3 B/RECM ground for
power circuitGround to
engine (Fig A)–0.5 – 1 volt Engine running
E19-10 B/BlSensor ground
for ECT sensorGround to
body (Fig A)–0.5 – 1 volt Engine running