This is a method in
which the trouble is located by using a manifold gauge set. Read the
manifold gauge pressure when the these conditions are
established.
TEST CONDITIONS
• |
Temperature at the air inlet with the switch
set at RECIRC is 30~35°C (86~95°F) |
• |
Engine running at
1,500rpm |
• |
Blower speed control knob on "4"
position |
• |
Temperature control knob on "COOL"
position |
It should be noted that the gauge indications
may vary slightly due to ambient temperature
conditions. |
1. |
Normally functioning refrigeration
system.
Gauge reading
: Low
pressure side : 0.15~0.25 MPa
(21.8~36.3 psi, 1.5~2.5 kgf/cm²) High pressure side
: 1.37~1.57 MPa (199~228 psi, 14~16
kgf/cm²)
|

|
2. |
Moisture present in refrigeration
system.

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
During
operation, pressure on low pressure side sometimes become a
vacuum and sometime normal
|
Moisture
entered in refrigeration system freezes at expansion valve
orifice and temporarily stops cycle, but normal state is
restored after a time when the ice melts
|
•
|
Drier in oversaturected
state |
•
|
Moisture in refrigeration system
freezes at expansion valve orifice and block circulation
of refrigerant | |
-
|
Remove moisture in cycle through
repeatedly evacuating
air |
-
|
Charge proper amount of new
refrigerant | |
|
3. |
Insufficient cooling

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Pressure low on both low and high
pressure sides |
•
|
Insufficient cooling
performance | |
Gas leakage
at some place in refrigeration system
|
•
|
Insufficient refrigerant in
system |
|
-
|
Check for gas leakage with gas
leak detector and repair if
necessary |
-
|
Charge proper amount of
refrigerant |
-
|
If indicated pressure value is
near 0 when connected to gauge, create the vacuum after
inspecting and repairing the location of the
leak | |
|
4. |
Poor circulation of refrigerant

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Pressure low in both low and high
pressure sides |
•
|
Frost on tube from receiver to
unit | |
Refrigerant
flow obstructed by dirt in drier
|
Condenser
clogged
|
Replace
drier
|
|
5. |
Refrigerant does not circulate

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Vacuum indicated on low pressure
side, very low pressure indicated on high pressure
side |
•
|
Frost or dew seen on piping before
and after receiver/drier or expansion
valve | |
•
|
Refrigerant flow obstructed by
moisture or dirt in refrigeration
system |
•
|
Refrigerant flow obstructed by gas
leakage from expansion
valve | |
Refrigerant
does not circulate
|
-
|
Clean out dirt in expansion valve
by blowing with air |
-
|
Evacuate air and charge new
refrigerant to proper
amount |
-
|
For gas leakage from expansion
valve, replace expansion
valve | |
|
6. |
Refrigerant overcharged or insufficient
cooling of condenser

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
Press too
high on both low and high pressure sides
|
•
|
Unable to develop sufficient
performance due to
excessive |
•
|
Insufficient cooling of
condenser | |
•
|
Excessive refrigerant in cycle →
refrigerant overcharged |
•
|
Condenser cooling → condenser fins
clogged or condenser fan
faulty | |
-
|
(2) Check cooling fan with fluid
coupling operation. |
-
|
(3) If (1) and (2) are in normal
state, check amount of refrigerant
Charge proper amount of
refrigerant | |
|
7. |
Air present in refrigeration
system

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Press too high on both low and
high pressure sides |
•
|
The low pressure piping hot to the
touch | |
Air entered
in refrigeration system
|
•
|
Air present in refrigeration
system |
•
|
Insufficient vacuum
purging | |
-
|
Check compressor oil to see if it
is see if it is dirty or
insufficient |
-
|
Evacuate air and charge new
refrigerant | |
|
8. |
Expansion valve improperly

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Pressure too high on both low and
high pressure sides |
•
|
Frost or large amount of dew on
piping on low pressure
side | |
Trouble in
expansion valve
|
•
|
Excessive refrigerant in low
pressure piping |
•
|
Expansion valve opened too
wide | |
|
|
9. |
Defective compression compressor

Symptom seen in
refrigeration system
|
Probable
cause
|
Diagnosis
|
Remedy
|
•
|
Pressure too high on low high
pressure sides |
•
|
Pressure too low to on high
pressure side | |
Internal
leak in compressor
|
•
|
Valve leaking or broken sliding
parts | |
Repair or
replace
compressor
|
|
INSPECT FOR LEAKAGE OF REFRIGERANT
Always conduct a leak
test with an electronic leak detector whenever leakage or refrigerant is
suspected and when conducting service operations which are accompanied by
disassembly or loosening or connection fittings.
In order to use the leak detector properly,
read the manual supplied by the
manufacturer. |
1. |
Check the torque on the connection fittings
and, if too loose, tighten to the proper torque. Check for gas
leakage with a leak detector. |
2. |
If leakage continues even after the fitting
has been tightened, discharge the refrigerant from the system,
disconnect the fittings, and check their seating faces for damage.
Always replace, even if the damage is
slight. |
3. |
Check the compressor oil and add oil if
required. |
4. |
Charge the system and recheck for gas leaks.
If no leaks are found, evacuate and charge the system
again

|
A/C SYSTEM TESTS
•
|
Air conditioning refrigerant or
lubricant vapor can irritate your eyes, nose, or
throat. |
•
|
Be careful when connecting service
equipment. |
•
|
Do not breathe refrigerant or
vapor. | |
•
|
Compressed air mixed with R-134a forms a
combustible vapor. |
•
|
The vapor can burn or explode causing
serious injury. |
•
|
Never use compressed air to pressure
test R-134a service equipment or vehicle air conditioning
systems. | |
1. |
Connect a R-134a refrigerant
recover/recycling/charging station to the high-pressure service port
and the low-pressure service port, following the equipment
manufacturer s instructions. |
2. |
Insert a thermometer in the center
vent.
Determine the relative humidity and air
temperature.

|
3. |
Test conditions :
A. |
Avoid direct
sunlight. |
D. |
Set the temperature control dial on MAX
COOL, the mode control switch on VENT and the recirculation
control switch on
RECIRCULATE. |
E. |
Turn the A/C switch on and the fan
switch on MAX. |
F. |
Run the engine at 1,500
rpm. |
G. |
No driver or passengers in
vehicle. | |
4. |
After running the air conditioning for 10
minutes under the above test conditions, read the delivery
temperature from the thermometer in the dash vent, the intake
temperature near the blower unit behind the glove box and the high
and low system pressure from the A/C
gauges. |
5. |
To complete the chart
A. |
Mark the delivery temperature along the
vertical line |
B. |
Mark the intake temperature along the
bottom line |
C. |
Draw a line straight up from the air
temperature to the humidity |
D. |
Mark a point 10% above and 10% below the
humidity level |
F. |
Draw a horizontal line across the
delivery temperature |
G. |
The delivery temperature should fall
between the two lines |
H. |
Complete the low side pressure test and
high side pressure test in the same
way |
I. |
Any measurements outside the line may
indicate the near for more further
inspection | |

REFRIGERANT RECOVERY
•
|
Air conditioning refrigerant or
lubricant vapor can irritate your eyes, nose, or
throat. |
•
|
Be careful when connecting service
equipment. |
•
|
Do not breathe refrigerant or
vapor. | |
1. |
Connect a R-134a refrigerant
recovery/recycling/charging station(A) to the high-pressure service
port(B) and the low-pressure service port(C), as shown, following
the equipment manufacturer s instruction.

|
2. |
Measure the amount of refrigerant oil removed
from the A/C system after the recovery process is completed. Be sure
to put the same amount of new refrigerant oil back into the A/C
system before charging. |
SYSTEM EVACUATION
•
|
Air conditioning refrigerant or
lubricant vapor can irritate your eyes, nose, or
throat. |
•
|
Be careful when connecting service
equipment. |
•
|
Do not breathe refrigerant or
vapor. | |
1. |
When an A/C System has been opened to the
atmosphere, such as during installation or repair, it must be
evacuated using a R-134a refrigerant recover/recycling/charging
station (If the system has been open for several days, the
receiver/dryer should be replaced, and the system should be
evacuated for several hours.) |
2. |
Connect a R-134a refrigerant
recovery/recycling/charging station(A) to the high-pressure service
port(B) and the low-pressure service port(C), as shown, following
the equipment manufacturer s instruction. Evacuate the
system.

|
3. |
If the low-pressure does not reach more than
93.3 kPa (700 mmHg, 27.6 in.Hg) in 15 minutes, there is probably a
leak in the system. Partially charge the system, and check for
leaks. |
SYSTEM CHARGING
•
|
Air conditioning refrigerant or
lubricant vapor can irritate your eyes, nose, or
throat. |
•
|
Be careful when connecting service
equipment. |
•
|
Do not breathe refrigerant or
vapor. | |
1. |
Connect a R-134a refrigerant
recover/recycling/charging station(A) to the high-pressure service
port(B) and the low-pressure service port(C), as shown, following
the equipment manufacture s instructions.

|
2. |
Add the same amount of new refrigerant oil to
the system that was removed during recovery. Use only FD46XG (PAG)
refrigerant oil |
3. |
Carge the system with the specified amount of
R-134a refrigerant. Do not overcharge the system; the compressor
will be damaged.
Refrigerant capacity : 600 ±
25g
| | |