Haier HB21FWRSS Service Manual page 33

Causes for troubles occurring in refrigerators are closely related to the quality of components
and workmanship in assembling by manufacturers as whether refrigerators are properly used
and maintained .The parameters generally used to express the working conditions of a
refrigerator include the temperature inside the refrigerator, operation rate, electric power
consumption, noise level, and other functional indexes .If any one of these parameters is
beyond its permissible range, this indicates that there is a fault or trouble in the refrigerator.
During the whole service life of a refrigerator, the probability of troubles occurring within a
union time is called its failure rate. Making a comparison between the control circuit system of
a refrigerator and its refrigerating system, we can find that the failure rate of the former is
higher, and that of the thermostat is the highest. In troubleshooting, the first thing you must
do is to determine where the trouble comes from --- the control system or the refrigerating
system. There is general no trouble indicating instrument mounted on the domestic
refrigerator, locations and natures of troubles should be determined according to their
respective features, therefore, experience in servicing is very important to troubleshooting.
Service technicians with rich experience can correctly locate them and take reasonable
remedy measures based on their comprehensive analysis of trouble characteristics as well as
operating conditions for various kinds of refrigerators.
Three Essentials for Checkup
1) Look
a) Check the tubing of refrigerating system for cracks and various welding points for leaks; if
leakage occurs, an oil stain can be seen definitely .
b) Check the suction and exhaust pressure values (high pressure and low pressure) of
compressor to see whether they are normal.
c) Check the conditions of frost attached to its evaporator and gas return tube .It is abnormal
if frost has formed on part of the evaporator or there is no frost attached to it. (This criterion
is not applicable to the evaporator of refrigerator compartment.)
d) Pay attention to the speed of temperature drop inside both the refrigerator compartment
and freezer compartment .It is abnormal if the speed of temperature drop is obviously slower
than the corresponding normal speed.
e) Check the environment to see whether it is suitable for placing a refrigerator.
f) Check refrigerator door seal, case, and table surface and heat insulation layer.
2) Listen
a) Listen to the noises produced when the compressor is running
Hums from a fully enclosed aggregate unit is the sound caused by overload indicating that the
motor cannot be started normally, meanwhile, a clattering sound can be heard from inside the
start relay, which is produced because the start contacts cannot be released normally
whistling sound is caused by the high pressure gas flowing out of the crack of the pressure
tube inside the compressor, and clucks are the sound of striking after the suspended spring
inside the compressor has broken.
During the normal operation of compressor, a slight and uniform hum sound due to
undulation of electric current can be heard generally, this is a normal phenomenon. However,
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