This is the first in a series of posts I’m going to do about the technology used in GE refrigerators. Understanding the basics of how these refrigerators work will give you a lot of troubleshooting insight when you’re trying to track down a problem. This post explains how the fans in GE refrigerators are controlled and operated.
Like most other refrigerators, GE refrigerators have at least two fans:
- the evaporator (freezer) fan
- the condenser fan (the hot coil in the back, underneath the refrigerator)
Some up-line GE models may have an additional fan:
- in the beer section if it’s a dual evaporator unit
- in the Custom Cool® compartment, if so equipped
All fan motors used in current model GE refrigerators (includes Hotpoint brand) operate on 12 vdc. The motor speed is controlled using a technology called Pulse Width Modulation (PWM). Simple explanation of PWM: take a square wave and vary the width of the upper side of the pulses according to how fast you want the motor to turn- the longer the pulse, the faster the speed. For details on how PWM technology works, see this page ==> http://www.netrino.com/Embedded-Systems/How-To/PWM-Pulse-Width-Modulation
Currently, the condenser fan is single speed (although that’s gonna change in upcoming models) and the evaporator fan is multispeed.
Fan Wire Harness Color Code
- Yellow: PWM signal (input)
- Blue: Tachometer (output from motor)
- Red: +12 vdc supply (input)
- White: Common Ground! Can I hears an “A-freakin-men?”
The PWM wire on the fan motor harness is always the yellow wire– this is the wire that carries the signal telling the fan how fast to spin. Don’t bother trying to measure the voltage on the yellow wire with a conventional meter because the results will be meaningless.
Quick n’ Sleazy Fan Test
- White wire to the negative battery terminal
- Connect BOTH the Red and Yellow wires to the positive battery terminal.
Do not reverse the leads or you’ll blow out the sensitive electronics built into the motor assembly!
Quick Fan Diagnostic Test
- you should never hear the the fan making speed varying sounds in side-by-side units
- on top-mount units, you can sometimes hear the fan making pulsing noises
Fan Circuit on the Muthaboard
Some of the Muthaboards used in these boxes have resistors in the power circuit for the fans. These will be two resistors coming off the J2 plug on the board. If you’re looking straight at the board, the top resistor is for the evaporator fan and the bottom one for the condenser fan. They’re designed to burn out in case one of the fan motors shorts out. If this happens, you’ll need to replace BOTH the affected fan motor as well as the Muthaboard.
Part Links for Your Shopping Pleasure
Evaporator and Condenser Fans ==> http://www.repairclinic.com/Shop-For-Parts?searchText=GE%20refrigerator%20fan%20motor&Search=Find%20Parts