Before replacing WR55X10942 – A Very Quick and Simple Measurement that May Solve Your Intermittent GE Refrigerator Problem

A Very Quick and Simple Measurement that May Solve Your Intermittent GE Refrigerator Problem

[ This article was originally posted at http://fixyourboard.com/techzone/refrigerators/ge_fridge_testload/ge_fridge_testload.html where you will find other articles of interest ]

At www.fixyourboard.com we repair a lot of GE fridge control boards with various component failures but there is one failure mode that we see often. This turns out to be responsible for a variety of seemingly random intermittent fridge problems that tend to be very hard to diagnose. Well, we came up with a very simple tool and procedure to isolate this problem on-site. It only requires one measurement with a DVM, nothing needs to be disconnected from the controller, only the control board cover panel need be removed.

Here I will describe the problem, how to construct this simple tool for about $3 and 10 minutes of your time, and how to make the measurement. This applies to the wide range of control board part numbers that look similar to this: Typical GE Motherboard

First: The Problem and The Test Strategy

The motherboard contains a 13.5 Vdc power supply that powers the relays, fans, dampers, etc as well as power to the temperature control board and dispenser board. There is a frequently occuring component failure that causes this power supply to still work fine under light loads, but lose its regulation ability under heavier loads. So suddenly, depending on the state of the fridge and what devices the motherboard is trying to energize, things go from working fine to … not so good … or major failure.

The test strategy is to make a voltage measurement on the connector (J4, pins 2-3) that supplies 13.5 Vdc to the other boards, AND TO DO SO UNDER FULL LOAD.

Next: The Test Load Device

Measure the voltage with a 25 ohm/10W shunt load to ferret out the problem (keep reading to see how to make the shunt load). A good board will see less than a few tenths Volt droop on this supply under load. A defective board will see a large drop in voltage (several Volts) when applying the load.

To be clear: If you see a supply voltage less than about 13.3 Volts under this condition then the motherboard has a problem. If the supply holds up under load, then the supply is good, but there could still be other problems with the motherboard. In a future blog I will deal with this. This is a quick NO-GO test.

If you think the supply may be bad but it’s not obvious, then also do a no-load measurement to check the difference. There should less than a few hundred millivolts difference between no-load and full load.

How to Contruct the Test Load

Here we build a 25 ohm, 10 Watt shunt load that plugs into the standard 3/4 inch spaced banana jacks on most DVMs. (OK, not all DVMs use this standard jack spacing, in which case you can add some short banana patch cords, or get a better meter). Following is a sequence of images showing how to construct the load, along with part numbers from www.mouser.com.

Last: Where to Measure

Backprobe connector J4 as shown below (the 2nd and 3rd pins from the edge). This is the 13.5 Vdc power supply to the other boards.

Summary

  • Backprobe the 13.5 Vdc supply on the connector J4, between pins 2 and 3 without the test load
  • Record the actual voltage (usually around 13.5 to 13.6 V)
  • Plug in the test shunt load between your meter and probes
  • Backprobe the same points and record the voltage under load
  • If you see more than a few tenths of a volt drop under load, then the motherboard has a problem
  • We can repair the control board for you at http://www.fixyourboard.com

GE Refrigerator Icing Up?

At www.FixYourBoard.com this is a common question regarding refrigerators; does my control board need to be reconditioned?  How do I isolate the problem to the control board or other parts such as thermistors, defrost heater or defrost over temperature thermostat?  I will try to help here:

This applies to General Electric SxS (Side by Side), Arctica, Profile, Monogram, Bottom-Mount refrigerators.  Model series are ETS22, ESS22, ESS25, GSS20, GSS22, GSS25, GTS22, HTS22, HSS22, HSS25, PTS22, PTS25, STS22, SSS25 and more.  Below is a troubleshooting flow chart from GE documentation.

Make sure the fridge is unplugged before going through this troubleshooting exercise.   A deeper explanation follows the flowchart.

Step – Unplug refrigerator.  Unplug connector J9 from the main board.  Measure between blue wire and connector and orange (neutral) wire on main control board J7 pin 9.  Are there approximately 37 ohms?

Explanation: This step measures the defrost heater.  By unplugging it from the board, you are left with the defrost heater, bi-metal defrost switch and wiring to the control board.  If the resistance is much higher than 37 ohms.  It is the switch, defrost heater or wiring that needs to be replaced.

Step – Verify thermistors are within proper range using thermistor values chart.  Is the resistance within range.

Explanation: Using a D.V.M. (digital volt meter), the thermistors must have a resistance that corresponds to the correct temperature.  This can be a little tricky because you don’t know the actual temperature of the thermistor.  Your values don’t have to be exact, but they should be in the ball park of what you think the temperature is.  Here are three relevant values:

Room temperature (77 degrees F)  – 5,000 ohms

Freezing ( 32 degrees F)                – 16,300 ohms

Evaporator cold ( 23 degrees F)    – 21,000 ohms

Freezer Fan Not Working – GE Refrigerator

This page addresses a common freezer fan problem with GE fridges.  Modern GE fridges use a main electronic control board to control 12V  fans.  A list of models for which this posting applies is shown at the end of this posting.

There are basically 3 reasons that can cause a fan not to work correctly.

1.  Freezer door switch or wiring to the switch is stuck in a position that signals the control board that the freezer door is open.

2.  Fan or wiring to fan has the problem.  There could be a short or open in the fan or wiring to the fan.   Also, the fan could have an obstruction that keeps it from spinning.

3.  Control Board is damaged

Checking the door switches:

For safety, I recommend checking the door switches with the fridge unplugged!!

Backprobe the connectors to perform the following procedure.

With fridge unplugged and the freezer door open, check the resistance between L1 and freezer switch pin 7 on J2 connector.  The resistance should be very low ( less than 10 ohms).  Now, close the door and re-measure the resistance between L1 and freezer switch pin 7.  It should now be open circuit( very high resistance).   If this is working, your freezer door switch is functioning.

Repeat the procedure above for the fresh food door switch.   With the fresh food door open, the resistance between L1 and pin 6 should be less than 10 ohms.  With the fresh food door closed the measurement should be open circuit.

If these door switch tests pass, go to the next step.

Check the Evaporator Fan and Wiring:

Now that you have verified that the door switches are working correctly, the next step is to check if the freezer/evaporator fan is the problem.  We will introduce a trick to force power to the fan and verify whether the problem is in the fan or fan wiring.  Using a paper clip like the one shown below,  we will short pin 8 (12 Volts) and pin 4 (control power to fan)  together on connector J2.

The following shows a picture of the paper clip installed.  Make sure that the paper clip is far enough into the connector that the metal paper clip is making contact with the metal inside the connector.

Now, plug in the fridge.  The freezer fan should stay on continuously.  If the freezer fan is not spinning, make sure that paper clip is pushed in far enough to make connections to the metal inside the connector.  If the fan still doesn’t spin or is spinning at a slow speed, the fan or wiring should be replaced.