Electrolux R134A - Checking the Adaptive Defrost Control

2-15
These models use a metal sheath heater to
remove accumulated frost from the freezer
evaporator and drain trough during a de-
frost cycle.
The defrost timer (models) energizes the
defrost heater every 8 hours of accumu-
lated compressor run time. When the tem-
perature in the thermostat area reaches ap-
proximately +43
o
F. the thermostat contacts
open the circuit to the defrost heater.
An ohmmeter check will determine if all
phases of the defrost cycle are functioning
properly. The defrost thermostat contacts
open at approximately +43
o
F. and close at
approximately +15
o
F.
The defrost thermostat has a 240K ohm re-
sistor connected internally across the two
terminals. This resistor permits checking
the defrost heater when the evaporator tem-
perature is +15
o
F. or higher.
An ohmmeter can be used to test the de-
frost heater and thermostat without disas-
sembling the freezer compartment even if
the evaporator temperature is +15
o
F. o r
higher. To check, proceed as follows:
1. Disconnect the unit from the power
source.
2. Open the fresh food door and remove
any items on the top shelf. Remove the
light shield and the fascia/radiant shield
mounting screws in the temperature
control housing. While holding the
front of the housing, remove the rear
mounting screw. Lower the control
housing.
Note: If the temperature control is open
(unit not running and you jumper L1 and
Test) the unit will cycle through the test
mode in two seconds and there will be no
watt draw.
Checking the Adaptive Defrost
Control
1. Disconnect the unit from the power
source.
2. Open the fresh food door and remove
any items on the top shelf.
3. Remove the light shield and the tem-
perature control housing (see steps 3
and 4 replacing the timer).
4. Connect the refrigerator to a wattme-
ter.
5. Make sure compressor is running (cold
control closed).
6. Using an insulated number 22 jumper
wire short between L1 and Test; this will
put the refrigerator into a defrost for
approximately 23 minutes.
7. The watt meter should read between
500 to 600 watts depending on the
model.