Motor Troubles And Other Electric Faults - Haier HB21FNN Service Manual

b) Check the compressor accessories, including its thermal protector and relay. In case the
thermal protector is damaged, the compressor cannot be powered on. If the relay is out of
order, the motor will not run and hum sound can be heard from it after the compressor is
turned on, in that case, shut it down immediately, otherwise, the motor windings will be
burned out in case this condition lasts longer.
c) Check the relay contacts and plugs to see if they are perfect and work reliably. Poor contact
may cause the motor not running or humming.
2) Check the circuit voltage to see whether it is normal.
Anal y sis of trouble
If the circuit voltage is obviously lower than its rated value, it will be difficult to start the motor,
and a hum sound can be heard from it.
Remedy
Measures the voltage with a voltmeter, if it is really too low, give directions to the user for
buying a stabilizer so as to step up the voltage, thus normal operation can be achieved.
3) Check the thermal relay t o s e e w h e t h e r i t s c o n t a c t s a r e c l o s e d .
Analysis of Trouble
The contacts of thermal relay sometimes may be open due to the leakage of temperature
sensing agent from the temperature sensor.
Remedy
Remove the relay cover to check up its contacts, if they are open, this means that the original
setting is not properly set or temperature sensing agent has leaked out of the temperature
sensor. Try to turn the adjusting stem of this value in the direction of the lower temperature
graduation, then check the contacts to see whether they are closed. If they are still not closed,
dismantle the temperature sensing disc and then immerse it into warm water to see whether
the contacts actuate, if not, it can be preliminarily determine that temperature sensing agent
has leaked out, and it must be replaced with a new thermostat.

4) Motor troubles and other electric faults

a) Motor windings have been b u rned or short-circuited between turns
Analysis of Trouble
When motor windings have been burned or short-circuited between turns, the fuse will be
blown repeatedly, and the blowout occurs particularly at the instant when you close the knife
switch.
Remedy
Check the terminals and the outer casing to see whether they are short-circuited, and measure
the resistance of each phase with an avometer. If short circuit occurs or the resistance of a
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