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SERVICE MANUAL
Model: HRF10WNDWW/HRF12WNDWW
24
Issue 2009-7-24
Rev. Ref0907S005V0
Measure 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 to see whether its contacts are closed.
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, and 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 burned 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 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 megameter can be used in this inspection, too. If the
insulation resistance is lower than 2 M
Ω
, 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.
