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Suzuki Grand Vitara JB416 / JB420. Manual - part 283

7B-23 Air Conditioning System:

High pressure gauge

Low pressure gauge

Condition

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 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 (Insufficient oil etc.) Check compressor.
Engine overheat

Check engine cooling system referring to
“Engine 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.

Air Conditioning System: 7B-24

11) Check inlet port temperature-to-outlet port temperature relationship using graph.

For example, if A/C evaporator inlet port temperature is 25

°C (77 °F) and center ventilation louver temperature is

°C (55.4 °F), their crossing point is within acceptable range as shown in the graph in this case, cooling

performance is satisfactory and proper.

12) If crossing point is out of acceptable range, diagnose trouble referring to the following table.

Thermometer at center duct

NOTE
If ambient temperature is within 25

°C (77 °F), it is possible to diagnose A/C system in detail referring

to the following table.

[A]

[B]

emp

. at Air Outlet of Center

entilation Louv

46.4

48.2

50.0

51.8

53.6

55.4

57.2

59.0

60.8

62.6

64.4

66.2

68.0

69.8

71.6

73.4

75.2

77.0

78.8

80.6

82.4

F C

C
F

“E”

“F”

Temp. near Air Inlet of HVAC unit

Humidity

Acceptable range

. at Air Outlet of Center

entilation Louv

46.4

48.2

50.0

51.8

53.6

55.4

57.2

59.0

60.8

62.6

64.4

66.2

68.0

69.8

71.6

73.4

75.2

77.0

78.8

80.6

82.4

F C

C
F

“E”

“F”

Temp. near Air Inlet of HVAC unit

Humidity

Acceptable range

I5JB0A720013-03

[A]: M16 engine model
[B]: J20 engine model

Condition

Possible Cause

Correction

Crossing point is higher
than acceptable 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
damper in cooling (heater) unit

Repair 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.

7B-25 Air Conditioning System:

Condition

Possible Cause

Correction

Manifold Gauge

MPa

(kg/cm

)

(psi)

Detail

M16 engine model

0.23 – 0.33

(2.3 – 3.3)

(33 – 47)

J20 engine model

0.22 – 0.31

(2.2 – 3.1)

(31 – 44)

M16 engine model

0.96 – 1.16
(9.6 – 11.6)

(136 – 165)

J20 engine model

1.10 – 1.45

(11.0 – 14.5)

(156 – 206)

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 desiccant.
Evacuate the A/C
system and recharge
with fresh refrigerant.

Normal:

M16 engine model

0.23 – 0.33

(2.3 – 3.3)

(33 – 47)

J20 engine model

0.22 – 0.31

(2.2 – 3.1)

(31 – 44)

↑ ↓

Abnormal:

Negative pressure

Normal:

M16 engine model

0.96 – 1.16
(9.6 – 11.6)

(136 – 165)

J20 engine model

1.10 – 1.45

(11.0 – 14.5)

(156 – 206)

↑ ↓

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 desiccant.
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 a gas 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.

Air Conditioning System: 7B-26

M16 engine model

0.35 – 0.45

(3.5 – 4.5)

(50 – 64)

J20 engine model

0.33 – 0.45

(3.3 – 4.5)

(47 – 64)

2.0 – 2.5

(20 – 25)

(285 – 355)

High pressure reading on
both low and high pressure
sides.

Overcharged A/C
system.
Faulty condenser
cooling operation.
Faulty radiator fan
operation.

Adjust refrigerant to
specified amount.
Clean condenser.
Inspect and repair
radiator 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 desiccant.
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

)

(psi)

Detail

Content .. 281 282 283 284 ..