18
Listen
a) Listen to the noises made while the compressor is running. During the normal operation of
compressor, a slight and uniform humming sound due to undulation of electric currents will
be heard. The sounds listed below indicate a malfunction.
i.
Humming sounds
from a fully enclosed aggregate unit indicate that the motor was not
started properly.
ii.
Clattering sounds
from the start relay indicate that the start contacts cannot be released
normally.
iii.
Whistling sounds
indicate the release of high-pressure gas from a crack in the pressure
tube inside the compressor.
iv.
Clucking sounds
indicate that the suspended spring inside the compressor has broken
v.
Knocking sounds
from inside the compressor indicates that a large quantity of moist
refrigerant vapor or refrigerating oil has leaked into the compressor cylinder.
vi.
Striking sounds
from metal parts inside the compressor indicate that moving parts are
loose.
b) Listen to the gas flowing in the evaporator by opening the refrigerator door while the
compressor is in operation. Normally, refrigerant circulating in the evaporator produces a
gentle whistling accompanied by a sound similar to water flowing. If only the whistling can
be heard and there is no sound similar to water flowing, then the refrigerant has already
percolated. If neither sound can be heard, the filter or capillary is clogged.
.
Touch and Feel
a) Feel the compressor while it is running. Its temperature should be less than 194ºF. Its
temperature may exceed 194ºF if it has been running for an extended period.
b) After the compressor has operated for 5~10 minutes, feel the condenser. The temperature of
its upper part should be higher than that of its lower part (or its right part is hotter than its left
part, depending on the type of condenser coil). This indicates that the refrigerant is
circulating properly. If the condenser is not hot, then the refrigerant is leaking. If the
condenser is hot for only a few minutes and then cools down, the filter and capillary are
clogged. If hot air is blown out of the forced air-cooling condenser, the system is out of
order.
c) Feel the filter’s temperature. Normally, the temperature on the filter’s surface should be a
little higher than the ambient temperature. If the filter is lower than the ambient temperature,
then the meshes of its screen are clogged. This obstructs the flow of refrigerant and causing a
drop in temperature due to throttling.
d) Feel the temperature of exhaust gas from the refrigerating system. The exhaust gas should be
extremely hot. If the refrigerator has an enclosed compressor refrigerating system, there
