Defrost Timer; To Remove Defrost Timer; To Check Defrost Timer; Defrost Thermostat - Electrolux BEVERAGE CENTER II Service Manual

DEFROST TIMER (MECHANICAL)
The timer motor is energized during the defrost and
compressor run cycles. The timer motor turns an internal
cam. The cam opens and closes the electrical circuits
to the compressor, evaporator fan motor, condenser fan
motor, and defrost heater.

To Remove Defrost Timer

1. Disconnect electrical supply to refrigerator.
2. Remove four screws securing housing to top of
refrigerator compartment.
3. Unplug molex connector coming from top of cabinet.
4. Unplug connector to Defrost Timer. It may be very
snug. Use pliers to pull it loose from timer.
5. Remove two screws securing timer to control
housing. (See Figure C12.)
6. Reverse procedure to complete repairs.
Figure C12

To Check Defrost Timer

NOTE: The Defrost Timer contains a capacitor in
series with the motor. Use a 10K ohm scale and
test as a capacitor.
1. Disconnect electrical supply to refrigerator.
2. Remove defrost timer.
3. With timer in compressor run cycle, check
continuity from terminals 1 and 4.
4. Rotate timer knob until a click is heard or infinite
resistance is present.
5. With timer in defrost cycle, continuity should be
present between terminals 1 and 2.
6. With ohmmeter, check resistance at, or between
terminals 1 and 3. (Refer to data sheet.)
To check the mechanical operation, connect the timer to
the multiconnector. With 120 VAC present at terminals
1 and 3, the timer knob will rotate (check after ten
minutes).

DEFROST THERMOSTAT

The defrost thermostat is a temperature sensing device.
Wired in series with the defrost timer and the evaporator
defrost heater, it senses the rise in evaporator
temperature during a defrost cycle and cycles the
defrost heater off after all frost is melted. It is calibrated
to permit a defrost cycle only when the temperature is
below a preset temperature. The contacts in the defrost
thermostat are set to open at 47°F and close at 25°F.
To Remove The Defrost Thermostat
1. Disconnect electrical supply to refrigerator.
2. Remove freezer shelves, ice bucket, ice trays and
baskets.
3. Remove Ice Maker/Ice Maker tray holder (2 screws)
in place on left wall of freezer.
4. Remove evaporator fan access cover (1 screw).
5. Remove evaporator coil cover (4 screws).
NOTE: Ensure that you disconnect the green
ground wire connected to the evaporator coil cover
on the bottom left hand corner.
6. Disconnect two leads to thermostat which is mounted
to upper left corner of evaporator.
7. Remove thermostat from evaporator.
8. Reverse procedure to complete repairs.
To Test The Defrost Thermostat
1. Measure resistance across two thermostat leads. At
room temperature, resistance should be infinity.
Contacts are open.
2. Place couple of ice cubes on sides of thermostat.
After few seconds, thermostat should reset.
3. Measure resistance again. This time, reading should
be 0. Contacts have closed.
4. If you get resistance readings that differ from those
listed in this procedure, replace defrost thermostat.
Contacts are probably burnt.

DEFROST HEATER

The defrost heater is a radiant "U" shaped resistance
heater, rated at 600 watts on some models. (See the
Service Data Sheet for correct wattage.) The defrost
heater is wired in series with the defrost thermostat and
contacts 2 to 1 of the defrost timer. The defrost heater is
energized during that period of the cycle when the defrost
thermostat contacts are closed.
The length of time the heater is energized depends on the
amount of frost accumulation on the evaporator.
NOTE: During the automatic defrost cycle, there
will be a red glow in the vents on the back wall of the
freezer compartment. This is normal during the
defrost cycle.
How To Remove The Defrost Heater (See Figure C13)
1. Disconnect electrical supply to refrigerator.
2. Remove freezer shelves, ice bucket, ice trays and
baskets.
3. Remove Ice Maker/Ice Maker tray holder (2 screws)
in place on left wall of freezer.
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