1540 / 1575
HVAC
43
HVAC
REFRIGERATION CYCLE TROUBLESHOOTING
Sr.
No.
Possible Cause
Remedy
3
Entry of moisture in
the refrigerant cycle
Condition
x
Air conditioner alternately cools and
does not cool.
Symptoms in refrigerant cycle
x
During operation, the pressure on the
low pressure side alternates between
vacuum and normal.
Cause
x
The moisture mixed in the refrigerant
in the refrigerating cycle freezes in the
expansion valve orifice, blocking the
cycle. After a time, the ice melts and
normal conditions return
Diagnosis
x
The drier is in an oversaturated condi-
tion.
x
The moisture in the refrigerating cycle
freezes the expansion valve orifice,
impeding refrigerant circulation.
Countermeasures
x
Remove the moisture by
repeated evacuation.
x
Recharge new refrigerant
to the specified amount.
4
Refrigerant fails to
circulate
Condition
x
Air conditioner does not cool.
Symptoms in refrigerant cycle
x
Pressure on the low pressure side is
vacuum
x
Pressure on the low pressure side is
vacuum low.
x
Frost or dew is formed on the piping
at the front and rear side of the re-
ceiver or the expansion valve.
Cause
x
Moisture or dirt in the refrigerating
cycle freezes or sticks to the expan-
sion valve orifice, obstructing
refrigerant flow.
x
Gas leaking from the heat sensitizing
tube of the expansion valve obstructs
refrigerant flow.
Diagnosis
x
Blocked expansion valve orifice.
Countermeasures
x
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
evacuation, Recharge new
refrigerant to the specified
amount.
x
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.