GE PSH23SGNAFBS Series Technical Service Manual

– 19 –The evaporator fan has a 4-wire connection:White Wire (DC Common)The white wire is the DC common wire used fortesting. During repairs, DC polarity must beobserved. Reversing the DC polarity will cause ashorted motor and/or board.Red Wire (Supply)Each motor uses an internal electronic controllerto operate the motor. Supply voltage from themain control board remains at a constant 12 VDC.Blue Wire (Feedback/RPM)On previous Arctica models, the blue wirereported rpm (speed) information to the maincontrol board for speed control purposes. On thismodel, the board does not require nor read anyfeedback information from the fan motor.Yellow Wire (Signal)The yellow wire is the input wire from the maincontrol board. The main control board provides6.5 VDC effective voltage for low speed, 8 VDCeffective voltage for medium speed, and 9.5 VDCfor high speed. The fan will operate in low speedonly 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 controllerb. Yellow to white - power for fan• Observe circuit polarity.• Motors can be run for short periods using a9-volt battery. Connect the white wire to thenegative (-) battery terminal only. Connect thered and yellow wires to the positive (+) batteryterminal.