Haier HB21T NN Service Manual page 40

certain phase is low, this means that short circuit does exist in the windings and/or between
turns, and insulation layers have been burned or deteriorated. A megametre can be used in
this inspection, too. If the insulation resistance is lower than 2 M , this means that the
insulation layer is already breakdown. If the motor has been burned, repair it or replaced it
with a new one.
b) Fault of control relay
Analysis of Trouble
Overheat, burnout or wear of control relay contacts may occur generally. All these will cause
poor contact in electricity.
Remedy
Dismantle it to repair, or replace it with a new one.
c) Poor electric contractor in thermostat
Analysis of Trouble
Burnout of contractor and leakage of temperature sensing agent may occur generally.
Remedy
Replace the old with a new one.
d) Check the terminals for loose connection and electric circuits for other abnormal
phenomena.
5) Mechanical faults of compressor
a) Seizing of shaft
This phenomenon is caused mostly by poor lubrication, such as insufficient quantity of
lubricant, clogging in the lubricant oil line, or intermittent lubricant oil supply. Dirt and other
impurities in the lubricant oil will increase its viscosity and cause the shaft to be seized.
Copper plating may also result in seizing of shaft.
b) Seizing of piston
This is caused by too small fit clearance between the piston and cylinder or expansion due to
heat.
Judgement of seizing shaft and piston: After the refrigerator has been powered on, the
compressor will not start and run, but a slight hum sound can be heard, and several seconds
later, thermal protective relay will actuate and make the contacts open; this process will occur
repeatedly, but the compressor cannot be started.
E. Compressor won't stop
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