422 / 801
FATC
35
Sr.
No.
OCCURANCE
POSSIBLE CAUSE
REMEDY
4
Refrigerant fails to
circulate
Condition
•
Air conditioner does not cool. Symp-
toms in refrigerant cycle
•
Pressure on the low pressure side is
vacuum
•
Pressure on the low pressure side is
vacuum low.
•
Frost or dew is formed on the piping at
the front and rear side of the receiver or
the expansion valve.
Cause
•
Moisture or dirt in the refrigerating cycle
freezes or sticks to the expansion valve
orifice, obstructing refrigerant flow.
•
Gas leaking from the heat sensitizing
tube of the expansion valve obstructs
refrigerant flow.
Diagnosis
•
Blocked expansion valve orifice.
Countermeasures
•
Allow to stand for some
time and then resume op-
eration to decide whether
the blockage is caused by
moisture or by dirt. If
caused by moisture; re-
move the moisture by
repeated, Recharge new
refrigerant to the specified
amount.
•
If cased by dirt; remove the
expansion valve and blow
out the dirt with com-
pressed air. If unable to
remove the dirt, replace
the expansion valve.
Evacuate and charge new
refrigerant to the specified
amount. If caused by gas
leaking from heat sensitiz-
ing tube, replace the
expansion valve
5
Expansion valve mal-
functioning (opening
too much).
Condition
•
Air conditioner does not cool effectively.
Symptoms in refrigerant cycle
•
Pressure on both the low and high.
Pressure sides is high.
•
Frost or heavy dew is formed on the
piping on the low pressure side.
Cause
•
The expansion valve is malfunctioning
Diagnosis
•
Excessive liquid refrigerant in the low
pressure side piping.
•
Expansion valve opened too far.
Countermeasures
•
Check the diaphram of ex-
pansion valve.
•
If the diaphragm is proper,
replace the expansion
valve.
6
Faulty compression of
compressor
Condition
•
Air conditioner does not cool. Symp-
toms in refrigerant cycle
•
Pressure on the low pressure sides is
too high and pressure on the high pres-
sure side is too low.
Cause
•
There is leaking in the compressor
Diagnosi
s
•
Faulty compression of compressor.
•
Delivery valve or packing is leaking or
broken or compressor is malfunctioning.
Countermeasures
•
Check the compressor oil
for contamination and
quantity.
•
Replace the compressor.