GE ETS22 Technical Service Manual page 23

The evaporator fan motor uses a 4-wire
connection, utilizing a common wire (white),
feedback/rpm wire (blue), supply wire (red), and
a signal wire (yellow).
White Wire (DC Common)
The white wire is the DC common wire used for
testing. During repairs, DC polarity must be
observed. Reversing the DC polarity will cause
a shorted motor and/or board.
Red Wire (Supply)
Each motor uses an internal electronic controller
to operate the motor. Supply voltage from the
main control board remains at a constant
12 VDC.
Blue Wire (Feedback/RPM)
The blue wire feeds rpm (speed) information to
the main control board, allowing the board to
maintain consistent fan speeds. Loss of
feedback from the blue wire will result in the fan
accelerating to maximum speed. Measure the
fan rpm using the frequency between the blue
and white wires.
High speed - 195 to 200 Hz
Medium speed - 145 to 160 Hz
Low speed - 70 to 85 Hz
Yellow Wire (Signal)
The yellow wire is the input wire from the main
control board. The main control board provides
4.6 VDC effective voltage for low speed, 8.1
VDC effective voltage for medium speed, and
12.6 VDC for high speed. The fan will operate
in low speed only when the fresh food thermistor
is satisfied.
Note: When testing these motors:
• You cannot test with an ohmmeter.
• DC common is not AC common.
• Verify 2 voltage potentials:
a. Red to white - power for internal
controller.
b. Yellow to white - power for fan.
• Observe circuit polarity.
• Motors can be run for short periods using a
9-volt battery. Connect the white wire to the
negative (-) battery terminal only. Connect the
red and yellow wires to the positive (+) battery
terminal.
Connector (To Main Control Board)
Evaporator Fan Connector
J2 (To Evaporator Fan and Condenser Fan)
Main Control Board
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Evaporator Fan