April 1998
41
RS590000 Rev. 0
Component Testing
Switch,
photosensitive
In series with cavity light switch and
cavity light. Senses low light condition to
complete circuit to cavity light.
Switch must not generate line conducted
noise or radiate inference more than
three feet on the AM, FM, VHF, or USH
Frequency bands.
1.
To check light sensor with cavity light switch on, cover light sensor eye.
Cavity lamp should light at approximately 50% of full illumination.
2.
If lamp fails to illuminate, activate water or ice dispenser switch. Lamp
should illuminate at full illumination and water or ice should be dispensed.
3.
If light illuminates, disconnect power and replace light sensor.
4.
If lamp does not illuminate, disconnect power and check cavity lamp and
socket.
Thermistor
Senses temperatures within refrigerator
and freezer compartments.
Check resistance across terminals. See tech sheet for bell curve resistance chart
at given temperatures.
Thermostat
Thermostat is in a series circuit with
defrost terminators, defrost heater, and
evaporator fan motor. Circuit is complete
if evaporator fan motor operates when
cold.
Controls the circuit from freezer
thermostat through defrost terminator to
defrost heater. Opens and breaks circuit
when thermostat senses preset high
temperature.
After defrost thermostat opens,
thermostat remains open until end of
defrost cycle and refrigerator starts
cooling again and defrost thermostat
senses a preset low temperature and
closes.
Test continuity across terminals.
With power off and evaporator coil below freezing, thermostat should check
continuous when checked with ohmmeter. See “Heater, evaporator (defrost)”
section for additional tests.
Timer, defrost
Timer motor operates only when freezer
control is closed. After specified amount
of actual compressor run time, inner cam
in timer throws the contacts from
terminal 4, the compressor circuit to
terminal 2, and defrost thermostat/defrost
heater circuit.
After 33 minutes of defrost cycle time,
timer cam resets the circuitry through
terminal 4 to compressor.
1.
To check timer motor winding, check for continuity between terminals 1 and
3 of timer.
2.
Depending on the rotation of the cam, terminal 1 of timer is common to both
terminal 2, the defrost modes, or terminal 1, the compressor mode. There
should never be continuity between terminals 2 and 4.
3.
With continuity between terminals 1 and 4, rotate timer knob clockwise until
audible click is heard. When the click is heard, the reading between
terminals 1 and 4 should be infinite and there should be continuity between
terminals 1 and 2.
4.
Continuing to rotate time knob until a second click is heard should restore
circuit between terminals 1 and 4.
Valve, water
Controls water flow to the ice maker and
cavity.
Check resistance across coil windings.
