Downloaded from www.Manualslib.com manuals search engine AIR CONDITIONING (OPTIONAL) 1B-3
General Description
Major Components and Location
1. Cooling unit 6. Suction hose 11. Foot air 16. Heater unit
2. Compressor 7. Receiver / dryer outlet pipe 12. Defroster air 17. A/C evaporator
3. Condenser assembly 8. Condenser outlet pipe 13. Demister air 18. Dual pressure switch
4. Receiver / dryer 9. Expansion valve 14. Fresh air 19. Low pressure service (charge) valve
5. Discharge hose 10. Ventilation air 15. Recirculation air 20. High pressure service (charge) valve
Downloaded from www.Manualslib.com manuals search engine 1B-4 AIR CONDITIONING (OPTIONAL)
Refrigerant Circulation
Refrigerant Type
Whether the A/C in the vehicle being serviced uses HFC-134a
(R-134a) or CFC-12 (R-12) is indicated on compressor label (1).
Also, it can be checked by the shape of the service (charge) valve
(2).
A: Liquid 1. Compressor 4. Receiver / dryer 7. Evaporator
B: Vapor 2. Magnet clutch 5. Dual pressure switch
C: Superheated vapor 3. Condenser assembly 6. Expansion valve
Downloaded from www.Manualslib.com manuals search engine 1B-6 AIR CONDITIONING (OPTIONAL)
Cool air won’t come
out or insufficient
cooling (A/C system
normal operative)Insufficient or excessive charge of
refrigerantCheck charge of refrigerant and system for
leaks.
Condenser clogged Check condenser.
A/C evaporator clogged or frosted Check A/C evaporator and A/C evaporator
thermistor.
A/C evaporator thermistor faulty Check A/C evaporator thermistor.
Expansion valve faulty Check expansion valve.
Receiver / dryer clogged Check receiver / dryer.
Compressor drive belt loosen or broken Adjust or replace drive belt.
Magnetic clutch faulty Check magnetic clutch.
Compressor faulty Check compressor.
Air in A/C system Replace receiver / dryer, and perform
evacuation and charging.
Air leaking from cooling unit or air duct Repair as necessary.
Heater and ventilation system faulty Check air inlet box (cooling unit), heater
control lever assembly and heater unit
referring to Section 1A.
Blower fan motor faulty Check blower fan motor referring to Sec-
tion 1A.
Excessive compressor oil existing in
A/C systemPull out compressor oil in A/C system cir-
cuit, and replace compressor.
Cool air won’t come
out only intermittentlyWiring connection faulty Repair as necessary.
Expansion valve faulty Check expansion valve.
Excessive moisture in A/C system Replace receiver / dryer, and perform
evacuation and charging.
Magnetic clutch faulty Check magnetic clutch.
Excessive charge of refrigerant Check charge of refrigerant.
Thermal switch faulty Check thermal switch.
Cool air comes out
only at high speedCondenser clogged Check A/C condenser.
Insufficient charge of refrigerant Check charge of refrigerant.
Air in A/C system Replace receiver / dryer, and perform
evacuation and charging.
Compressor drive belt loosen or broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Cool air won’t come
out only at high speedExcessive charge of refrigerant Check charge refrigerant.
A/C evaporator frosted Check A/C evaporator and A/C evaporator
thermistor.
Insufficient velocity of
cooled airA/C evaporator clogged or frosted Check A/C evaporator and A/C evaporator
thermistor.
Air leaking from cooling unit or air duct Repair as necessary.
Blower fan motor faulty Check blower fan motor referring to Sec-
tion 1A.
Wiring or grounding faulty Repair as necessary. Condition Possible Cause Correction
Downloaded from www.Manualslib.com manuals search engine 1B-8 AIR CONDITIONING (OPTIONAL)
Abnormal noise from crankshaft pulley
Abnormal noise from tension pulley
Abnormal noise from A/C evaporator
Abnormal noise from blower fan motor
Condition Possible Cause Correction
A large rattling noise
is heard at idle or sud-
den acceleration.Loosen crankshaft pulley bolt. Retighten bolt.
Condition Possible Cause Correction
Clattering noise is
heard from pulley.Worn or damaged bearing. Replace tension pulley.
Pulley cranks upon
contact.Cracked or loose bracket. Replace or retighten bracket.
Condition Possible Cause Correction
Whistling sound is
heard from A/C evapo-
rator.Depending on the combination of the interior /
exterior temperatures, engine rpm and refriger-
ant pressure, the refrigerant flowing out of the
expansion valve may, under certain conditions,
make a whistling sound.At times, slightly decreasing refrig-
erant volume may stop this noise.
Inspect expansion valve and
replace if faulty.
Condition Possible Cause Correction
Blower fan motor
emits a chirping
sound in proportion to
its speed of rotation.Worn or damaged motor brushes or commuta-
tor.Repair or replace blower fan motor.
Fluttering noise or
large droning noise is
heard from blower fan
motor.Leaves or other debris introduced from fresh air
inlet to blower fan motor.Remove debris and make sure that
the screen at fresh air inlet is intact.
Downloaded from www.Manualslib.com manuals search engine 1B-10 AIR CONDITIONING (OPTIONAL)
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
Downloaded from www.Manualslib.com manuals search engine 1B-12 AIR CONDITIONING (OPTIONAL)
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
Downloaded from www.Manualslib.com manuals search engine AIR CONDITIONING (OPTIONAL) 1B-13
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.
Downloaded from www.Manualslib.com manuals search engine 1B-14 AIR CONDITIONING (OPTIONAL)
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