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General Description
Refrigerant Type IdentificationS7RS0B7211001
Whether the A/C system in the vehicle uses HFC-134a (R-134a) or CFC-12 (R-12) is indicated on label (1) on the
compressor. Also, it can be checked by th e shape of the service (charge) valve (2).
[A]: HFC-134a (R-134a) [B]: CFC-12 (R-12)
I4RS0A720002-01
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Sub-Cool A/C System DescriptionS7RS0B7211003
In the sub-cool A/C system (condenser integrated with receiver/dryer), the inside of the condenser is divided into the
condensation part and the sub-cooler part, and the receiver/dryer is located between those. In the receiver/dryer, the
refrigerant is separated into the vapor refrigerant and the liqui d refrigerant. Only the liquid refrigerant is delivered to the
sub-cooler part of the condenser. The refrigerant is supercooled by the sub-cooler part of the condenser.
A/C Operation DescriptionS7RS0B7211004
ECM controls the radiator fan relay and the compressor relay by following signals.
• ON/OFF signal of A/C switch
• A/C refrigerant pressure sensor
• Evaporator thermistor (evaporator temperature sensor)
• ECT sensor
NOTE
The signal of A/C swit ch is fed from BCM to ECM usin g CAN communication system. For CAN
communication system, refer to “CAN Communication System Description in Section 1A”.
I7RS0A721001-01
[A]: Liquid 2. Magnet clutch 6. Expansion valve10. Desiccant
[B]: Vapor 3. Condenser 7. A/C evaporator11. Filter
[C]: Superheated vapor 4. Receiver/dryer (Modulator) 8. Condensation part12. Vapor refrigerant
1. Compressor 5. Refrigerant pressure sensor 9. Sub-cooler part 13. Liquid refrigerant
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Schematic and Routing Diagram
Major Components of A/C SystemS7RS0B7212001
Airflow diagram
Major components of A/C system
I4RS0A720003-01
7
2
34
1 8
6
5
I4RS0B720002-01
1. HVAC unit 5. Discharge hose9. Side ventilation air 13. Side defroster air
2. Compressor 6. Suction hose10. Center ventilation air 14. Fresh air
3. Condenser assembly 7. Liquid pipe11. Foot air 15. Recirculation air
4. Receiver/dryer (Modulator) 8. Expansion valve12. Front defroster air 16. Evaporator
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Cool air does not come
out or insufficient cooling
(A/C system normal
operation)Insufficient or excessive charge of
refrigerant
Check the amount of refrigerant and system
for leaks.
Condenser clogged Check condenser referring to “Condenser
Assembly On-Vehicle Inspection”.
A/C evaporator clogged or frosted Check A/C evaporator and evaporator
thermistor (evaporator temperature sensor)
referring to “Evaporator Inspection” and
“Evaporator Thermistor (Evaporator
Temperature Sensor) Inspection”.
Evaporator thermistor (Evaporator
temperature sensor) faulty Check evaporator thermistor (Evaporator
temperature sensor) referring to “Evaporator
Thermistor (Evaporator Temperature Sensor)
Inspection”.
Expansion valve faulty Check expansion valve referring to “Expansion
Valve Inspection”.
Desiccant clogged Replace receiver/dryer.
Compressor drive belt loosened or
broken Adjust or replace drive belt.
Magnet clutch faulty Check magnet clutch referring to “Magnet
Clutch Inspection”.
Compressor faulty Check compressor.
Air in A/C system Replace receiver/dryer, and then perform
evacuation and charge referring to “Operation
Procedure for Refrigerant Charge”.
Air leaking from HVAC unit or air duct Repair as necessary.
Heater and ventilation system faulty Check HVAC unit.
Blower motor faulty Check blower motor referring to “Blower Motor
Inspection in Section 7A”.
Excessive compressor oil in A/C system Drain excessive compressor oil from A/C
system circuit and compressor.
Cool air does not come
out only intermittently Wiring connection faulty
Repair as necessary.
Expansion valve faulty Check expansion valve referring to “Expansion
Valve Inspection”.
Excessive moisture in A/C system Replace receiver/dryer, and then perform
evacuation and charge referring to “Operation
Procedure for Refrigerant Charge”.
Magnet clutch faulty Check magnet clutch referring to “Magnet
Clutch Inspection”.
Excessive amount of refrigerant Check the amount of refrigerant.
Cool air comes out only
when driving vehicle at
high speed Condenser clogged
Check condenser referring to “Condenser
Assembly On-Vehicle Inspection”.
Insufficient charge of refrigerant Check the amount of refrigerant and system
for leaks.
Air in A/C system Replace receiver/dryer, and then perform
evacuation and charge referring to “Operation
Procedure for Refrigerant Charge”.
Compressor drive belt loosened or
broken Adjust or replace drive belt.
Compressor faulty Check compressor.
Cool air does not come
out only when driving
vehicle at high speed Excessive amount of refrigerant
Check the amount of refrigerant.
A/C evaporator frosted Check A/C evaporator and evaporator
thermistor (evaporator temperature sensor)
referring to “Evaporator Inspection” and
“Evaporator Thermistor (Evaporator
Temperature Sensor) Inspection”.
Condition Possible cause Correction / Reference Item
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Abnormal Noise from Tension Pulley
Abnormal Noise from A/C Evaporator
Abnormal Noise from Blower Motor
A/C System Performance InspectionS7RS0B7214003
1) Confirm that vehicle and environmental conditions are as follows.
• Vehicle is put indoors.
• Ambient temperature is within 25 – 35 °C (77 – 95
° F).
• Relative humidity is within 30 – 70%.
• There is no wind indoors.
• HVAC unit is normal.
• Blower motor is normal.
• There is no air leakage from air ducts.
• Condenser fins are clean.
• Air filter in HVAC unit is not clogged with dirt and
dust.
• Battery voltage is about 12 V.
• Radiator cooling fan operates normally.
2) Make sure that high pressure valve (1) and low pressure valve (2) of manifold gauge are firmly
closed.
3) Connect high pressure charging hose (3) to high pressure service valve (5) on vehicle and low
pressure charging hose (4) to low pressure service
valve (6).
4) Bleed the air in charging hoses (3) and (4) by loosening their nuts respectively utilizing the
refrigerant pressure. When a hissing sound is heard,
immediately tighten nut.
CAUTION!
Do not connect high and low pressure
charging hoses in reverse.
Condition Possible cause Correction / Reference Item
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.
ConditionPossible cause Correction / Reference Item
Whistling sound is heard
from A/C evaporator Depending on the combination of the
interior / exterior temperatures, engine
rpm and refrigerant pressure, the
refrigerant flowing out of the expansion
valve may, under certain conditions,
make a whistling sound At times, slightly decrea
sing refrigerant volume
may stop this noise.
Inspect expansion valve and replace if faulty.
Condition Possible cause Correction / Reference Item
Blower motor emits a
chirping sound in
proportion to its speed of
rotation Worn or damaged motor brushes or
commutator
Replace blower motor.
Fluttering noise or large
droning noise is heard
from blower motor Leaves or other debris introduced from
fresh air inlet to blower motor
Remove debris and make sure that the screen
at fresh air inlet is intact.
53
2
1
4 6
I4RS0A720006-01
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High pressure gauge
Low pressure gaugeCondition Possible cause Correction
Pressure is higher than
acceptable range
(“A” area) Refrigerant overcharged Recharge.
Expansion valve frozen or clogged Check expansion valve.
Clogged refrigerant passage of high pressure side Clean or replace.
Radiator cooling fan malfunction
(Insufficient cooling of condenser)
Check radiator cooling fan.
Dirty or bent condenser fins
(Insufficient cooling of condenser) Clean or repair.
Compressor malfunction (Insuffi cient oil etc.) Check compressor.
Engine overheat Check engine cooling system
referring to “Engin
e Cooling Symptom
Diagnosis in Section 1F”.
Pressure is lower than
acceptable range
(“B” area) Insufficient refrigerant
(Insufficient charge or leakage)
Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction
(valve opens too wide) Check expansion valve.
Compressor malfunction
(Insufficient compression) 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 compression) Check compressor.
Pressure is lower than
acceptable range
(“D” area) Insufficient refrigerant
(Insufficient charge or leakage)
Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction
(valve opens too narrow) Check expansion valve.
Clogged refrigerant passage (crashed pipe) Repair or replace.
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ConditionPossible cause Correction
Manifold gauge MPa (kg/cm2) (psi)
Detail
Lo Hi
0.27 – 0.43
(2.7 – 4.3)
(38 – 61) 1.59 – 1.94
(15.9 – 19.4)
(226 – 276)
Normal condition — —
Negative pressure 0.5 – 0.6
(5 – 6)
(71.2 – 85.3) The low pressure side
reads a negative
pressure, and the high
pressure 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
expansion valve,
preventing the
refrigerant from
flowing.Clean expansion
valve.
Replace it if it cannot
be cleaned.
Replace receiver/
dryer.
Evacuate the A/C
system and recharge
with fresh refrigerant.
Normal:
0.27 – 0.43
(2.7 – 4.3)
(38 – 61)
↑ ↓
Abnormal:
Negative pressure Normal:
1.59 – 1.94
(15.9 – 19.4)
(226 – 276)
↑
↓
Abnormal:
0.7 – 1.0
(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.
0.05 – 0.15
(0.5 – 1.5)
(4.2 – 21.3) 0.7 – 1.0
(7 – 10)
(100 – 142) Both low and high
pressure sides indicate
low readings.
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
manifold gauges are
attached, check for
any leaks, repair
them, and evacuate
the system.
0.4 – 0.6
(4 – 6)
(56.9 – 85.3) Pressure on low pressure
side is high.
Pressure on high
pressure side is low.
Both pressure becoming
equal right after A/C is
turned OFF.
Internal leak in
compressor.
Inspect compressor
and repair or replace
as necessary.
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A/C System Inspection at ECMS7RS0B7214004
Voltage Check
When checking voltage at ECM connector terminals related to A/C system, refer to “DTC P2101: Throttle Actuator
Control Motor Circuit Range / Performance in Section 1A”.
0.40 – 0.45
(4.0 – 4.5)
(57 – 64)
2.0 – 2.5
(20 – 25)
(285 – 355) High pressure reading on
both low and high
pressure sides.
Overcharged A/C
system.
Adjust refrigerant to
specified amount.
Faulty condenser
cooling operation. Clean condenser.
Faulty radiator cooling
fan operation. Inspect and repair
radiator cooling fan.
High pressure reading on
both low and high
pressure sides.
Low pressure side tubing
is not cold when touched. Presence of air in A/C
system
(Improperly
evacuated).Replace receiver/
dryer.
Inspect quantity of
compressor oil and
presence of
contaminants in oil.
Evacuate system and
recharge with fresh
refrigerant.
0.45 – 0.55
(4.5 – 5.5)
(64 – 78) High pressure reading on
both low and high
pressure sides.
Large amount of frost or
dew on the low pressure
side tubing.Faulty expansion
valve.
Refrigerant flow is not
regulated properly.
Replace expansion
valve.
Condition
Possible cause Correction
Manifold gauge MPa (kg/cm
2) (psi)
Detail
Lo Hi