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Acura CSX. Manual - part 497

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21-102

Climate Control

80 %

HUMIDITY
LEVEL

°C
(°F)

49
(120)

psi
(kPa)

60
(414)

45
(310)

25
(172)

LOW SIDE
(SUCTION)
PRESSURE

35
(95)

Ambient (Intake) Temperature vs. Low Side (Suction) Pressure

AMBIENT (INTAKE) TEMPERATURE

30 %

50
(345)

30
(207)

15
(103)

55
(379)

40
(276)

35
(241)

20
(138)

10
(69)

5
(34)

46
(115)

43
(110)

41
(105)

38
(100)

32
(90)

29
(85)

27
(80)

24
(75)

21
(70)

18
(65)

16
(60)

12. To complete the low side (suction pressure)/ambient air (intake) temperature chart:

• Mark the low side (suction pressure) temperature along the vertical line.
• Mark the ambient air (intake) temperature along the bottom line.
• Draw a vertical line from the ambient air (intake) temperature mark.
• Draw a horizontal line from the vent (delivery) temperature mark unit it intersects the vertical line.

NOTE: The low side and intake temperatures should intersect in the shaded area within about 10 % of the
measured humidity level. Any measurements outside the line may indicate the need for further inspection.

08/08/21 14:44:56 61SNR030_210_0103

Pressure Test

Test results

Related symptoms

Probable cause

Remedy

21-103

•

Suction and
discharge pressures
are normal

Warm air from the vents.

The A/C system
contains too much
refrigerant oil.
The air mix door is
not operating
properly.

Recover refrigerant (see page 21-90)
and evacuate the system (see page
21-91). Adjust the amount of oil in
the system, then recharge the
system (see page 21-92).
Check air mix door operation
(see page 21-72), and repair as
needed.

Suction and
discharge pressures
are roughly equal
and steady

The suction and
discharge pressures
equalize when the engine
is revved.

The A/C compressor
clutch or the drive
belt is slipping, or the
compressor shaft
seal is leaking.

Check whether the A/C compressor
clutch or the drive belt is slipping.
If the drive belt is slipping, replace
the drive belt (see page 4-31). Also
inspect the drive belt auto-tensioner
(see page 4-31).
If the A/C compressor clutch is
slipping, replace it (see page 21-86).
Check the A/C compressor shaft seal.
If it’s leaking, replace the A/C
compressor (see page 21-83).

Suction and
discharge pressures
are roughly equal but
fluctuate

Suction and discharge
pressures fluctuate while
running. Pressures
equalize as soon as the
A/C compressor
disengages.

The compressor
discharge valve or
the compressor
gasket is faulty.

Replace the A/C compressor (see page
21-83).

Suction and
discharge pressures
are roughly equal
and abnormally low

The suction and
discharge pressures do
not change during
continued operation.

The A/C system is
undercharged.

Recover refrigerant (see page 21-90),
then do the refrigerant leak check
(see page 21-93). Repair any leaks,
then recharge the system (see page
21-92).

Suction and
discharge pressures
are abnormally high,
but normalize when
the condenser is
cooled

The suction pressure
decreases when cool
water is sprayed on the
A/C condenser.

The A/C system is
overcharged.

Recover refrigerant (see page 21-90),
evacuate the system (see page 21-91),
and recharge the system to
specifications (see page 21-92).

08/08/21 14:44:56 61SNR030_210_0104

Test results

Related symptoms

Probable cause

Remedy

21-104

Climate Control

•

Suction and
discharge pressures
are abnormally high,
and refrigerant line
temperatures are
abnormal

The high pressure
vapor line to the
condenser is too hot.
The low pressure liquid
line from the
expansion valve is not
cold.
There is an abrupt
temperature drop
along a refrigerant line,
or in the condenser or
evaporator.

The A/C system
refrigerant flow is
restricted.

Replace the restricted line or
component.

Suction and
discharge pressures
are abnormally high,
but drop rapidly
when the
compressor
disengages

After stopping the A/C
compressor, the
discharge pressure
quickly drops about
196 kPa (28 psi), then
falls gradually.
The input and output
temperatures at the
expansion valve are
not similar.

There is excess air in
the A/C system.

Recover refrigerant (see page 21-90),
evacuate the system (see page 21-91),
and recharge the system (see page
21-92).

Suction and
discharge pressures
are abnormally high,
and there is little or
no airflow through
the A/C condenser

The condenser
and/or radiator fins
are clogged.
The condenser fins
are damaged.
The condenser
and/or radiator
fans are not
working properly.

Clean debris from the condenser
and/or radiator fins.
Comb the condenser fins to repair
any damage.
Troubleshoot the A/C condenser fan
and/or the radiator fan circuit(s).

The suction pressure
is high and the
discharge pressure is
low. Both pressures
are steady

The liquid line
temperature is similar
on both sides of
expansion valve.
System pressures do
not vary at a steady
engine speed.

The expansion valve
is stuck open.

Replace the expansion valve (see page
21-80).

The suction pressure
is low, the discharge
pressure is high, and
the refrigerant
temperature changes
abnormally
somewhere in the
system

The high pressure
liquid line going into
the expansion valve is
cold.
There is an abrupt
temperature drop in
the line between the
compressor and the
condenser, or in the
line between the
condenser and the
expansion valve.

The A/C system
refrigerant flow is
restricted.

Replace the restricted line or
component.

08/08/21 14:44:56 61SNR030_210_0105

Test results

Related symptoms

Probable cause

Remedy

21-105

•

The suction pressure
is high, the discharge
pressure is low, and
there are particle
contaminants in the
refrigerant lines

The expansion valve
and/or the compressor
discharge hose are
contaminated with metal
flakes or desiccant
particles.

The A/C compressor
is malfunctioning.

Replace the A/C compressor (see page
21-83). If the system is contaminated
with desiccant, replace the receiver/
dryer (see page 21-89).

The suction pressure
is high, the discharge
pressure is low, and
the pressures quickly
change when the A/C
disengages

The discharge and
suction pressures
equalize soon after the
A/C compressor stops.

The A/C compressor
seal is faulty.

Replace the A/C compressor (see page
21-83).

Suction and
discharge pressures
are both low and
none of the
refrigerant lines are
cold

There is no frost on the
expansion valve, and the
low-pressure liquid line is
not cold.

The A/C system has a
leak (very low
refrigerant charge).

Do the refrigerant leak check
(see page 21-93), repair any leaks, and
recharge the A/C system (see page
21-92).

Suction and
discharge pressures
are both low, and the
expansion valve or
the suction line is
abnormally cold

The temperature
around the expansion
valve is too low
compared to the
temperature around
the receiver/dryer.
The low pressure
(suction) hose/line is
cooler than the
evaporator.

The discharge hose/
line is clogged or
kinked, which is
restricting refrigerant
flow.
The suction hose/line
is clogged or kinked,
which is restricting
refrigerant flow.

Repair or replace the faulty A/C line
(see page 21-8).

Initially, the suction
and discharge
pressure are normal,
but both become
abnormally low
during operation

During extended
operation, the air flow
from the vents decreases.

The evaporator is
freezing up.

Run the fan with A/C compressor off to
warm the evaporator, then test the
evaporator temperature sensor
(see page 21-70). If necessary, replace
the evaporator temperature sensor.

Suction and
discharge pressures
are both low and
there are abnormal
temperature changes
at the expansion
valve

During extended
operation, warm air
comes out of the vents,
the suction pressure
decreases, and heavy
frost occurs on the low
pressure liquid line.
The low pressure liquid
line is cold at the
expansion valve, but
warm after the valve.
There is frost on the
expansion valve.

The expansion valve
is stuck closed.

Replace the expansion valve
(see page 21-80), and the receiver/
dryer (see page 21-89).
Check the old expansion valve for
contamination. If contaminants are
found, replace the component that
caused the contamination.

08/08/21 14:44:57 61SNR030_210_0106

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