Amana ATX 518 VW Service Manual page 28

Component Testing
Component Description
Switch, moisture Two position, single throw switch in
control (energy series with hot side of circuit.
saver)
OFF position opens circuit to heater.
ON position closes circuit to heater.
Consumer controls setting of switch.
Thermostat Thermostat is in a series circuit with
terminal 2 of defrost timer, 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. Defrost thermostat senses
a preset low temperature and resets
(closes).
Timer, defrost Timer motor operates only when freezer
control is closed.
After specified amount of actual
operating time, inner cam in timer throws
the contacts from terminal 4, compressor
circuit, to terminal 2, defrost
thermostat/defrost heater circuit.
After specificed defrost cycle time, timer
cam resets the circuitry through terminal
4 to compressor.
Valve, water Controls water flow to the ice maker.
Controlled by thermostat in ice maker.
See Ice Maker Section for further
information.
RS5280001 Rev. 0
Test Procedures
To check switch:
1. Place switch in OFF position.
2. Read resistance from red lead to violet lead. Should indicate open circuit.
3. Place switch in ON position.
4. Resistance from red to violet should read less than 1 ohm.
Test continuity across terminals.
With power off and evaporator coil below freezing, thermostat should show
continuity when checked with ohmmeter. See " Heater, evaporator (defrost)"
section for additional tests.
1. To check timer motor winding, check for continuity between terminals 1 and
3 of timer.
2. Depending on rotating position of the cam, terminal 1 of timer is common to
both terminal 2, the defrost modes, or terminal 4, 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, 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.
Check resistance across coil windings.
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