(Sorry this got so long but I wanted to get as much info in the post as possible.)



I have a french door Whirlpool Gold refrigerator model #GX5FHTXVY06 that I got in 2012. This model has the "Jazz" control board that is supposed to control an adaptive automatic defrost cycle.

I believe I have a defrost system problem. The symptoms are frost forming on the back wall of the freezer, which eventually builds up on the evaporator "fins" clogging it with ice build up which blocks airflow across/through the fins via the evaporator fan causing the refrigerator compartment to fail to cool the food.

Since the first of the year I've manually defrosted the freezer area with hair dryers three times. (I am getting quite speedy at taking apart the freezer and accessing the evaporator area.) The second time cleared the ice off the evaporator I searched the internet for answers and found the tech sheet for my model which describes the Control Board Troubleshooting and Service Mode diagnostics, including how to force the refrigerator into the defrost mode. I thought if I ran the forced defrost mode several times a week I could avoid ice build up and confirm the defrost circuit worked. In other words, if the defrost circuit worked when I forced it to turn on I would know the adaptive automatic defrost circuit of the jazz board was broken.

So several times a week I would manually force the refrigerator into the "short" defrost mode before going to bed. When I invoked the defrost mode I could hear ticking which I assumed was the defrost mode kicking in. The next morning by looking through the slits in the freezer's back panel I could see there was some clearing of ice on the evaporator fins. But over time I could see ice building up. I would force the defrost mode and some of the ice would clear but then it would come back. After a month or so of doing this I discovered I could switch the jazz board from automatic defrost mode to fixed time interval defrost mode. (Service Test #9). Surely this would clear the ice on the evaporator.

Apparently not, as there would be ice forming on the evaporator fins. I began to use the "long" forced defrost mode when going to bed. So, a long defrost cycle at night coupled with the fixed time interval defrost cycle. Still, after a week or so of doing this the food in the refrigerator began to get warm. I've just done another manual defrost and while the back cover was off the freezer I did some diagnostics using an ohmmeter.

1. The heater element is measuring 27 ohms. I figure that means it is operational. However, when I attempted to force the defrost mode I could not get the heater to turn on. (I had taped the light switch to the freezer compartment to the off position.) I held the edge of an ice cube onto the heater element and it did not melt the ice cube.

2. When the freezer was defrosted I measured the short/open status of the defrost thermostat. It indicated it was Open (infinite resistance.) I turned a can of compressed air upside down and sprayed the defrost thermostat with the freezing spray. This caused the defrost thermostat to go to the Closed position (Ohmmeter read 1 ohm). I allowed the thermostat to warm up again, and again it indicated it was Open. I figured the defrost thermostat was working. I then mixed up a cup of ice water and submerged the defrost thermostat in the mixture. I could not get the defrost thermostat to the closed position. I left it in the ice water bath for 10 minutes. I figured the ice bath was not cold enough to get the thermostat to close, and assumed the thermostat was good.

I reassembled everything and plugged the refrigerator back in. I set the Jazz board to Fixed Defrost mode (Service test #9). The next morning I ran Service Tests #1 through #6 and all the tests showed good operation of the refrigerator.

As of today the refrigerator is in fixed time interval defrost mode, I believe the defrost circuit is working, and I'm crossing my fingers that the ice build up will not come back.

1. What is going on with my refrigerator? It's likely the jazz board needs to be replaced, but shouldn't my efforts using the manual defrost mode and the fixed time defrost intervals work to keep the freezer defrosted? In other words, I don't want to buy the new jazz board and have the problem with the freezer not defrosting.

2. If the jazz board adaptive defrost mode is defective does that mean setting it to fixed time interval mode is also broken?

3. When I had the freezer apart, should the defrost thermostat have closed after being in an ice bath for 10 minutes? (Note: After defrosting and having been plugged in for a couple hours when I run the Service Test #1, it shows the defrost thermostat is closed.)

4. Why didn't the defrost heater turn on and melt the ice cube when I invoked the manual defrost mode when I had the freezer disassembled?

5. Is there any way to be sure the defrost heater is actually turning on without taking apart the freezer compartment?

Any help would be much appreciated as I'm getting to the end of my rope with this refrigerator.

I'm trying to avoid buying a $200 replacement part until I'm certain the defrost circuit works. Maybe the board is good but the defrost circuit is bad?

The only thing I know for certain is the heater is reading 27 ohms, and the thermostat closed when freezing liquid was sprayed on it. But with the refrigerator set in the forced defrost mode, it did not melt an ice cube held against the heating element. The thermostat did not close when it was submerged in an ice bath for 10 minutes. Why not?

When I go into the force defrost mode the compressor quits running. If the compressor didn't quit running it means the Jazz board is definitely defective. But it does quit running.

The Jazz board is set to Fixed defrost mode, meaning it will defrost every 8 to 10 hours or so (time interval is sketchy, I've gotten different answers when Googling). So far I'm not seeing ice build up on the evaporator fins, but it's only been 3 days.

It's been a week now. There is a slight amount of frost on the back panel of the freezer but so far the evaporator fins still look clear of ice. I think I'm just going to bite the bullet and buy the new Jazz board. $200 gone. <sigh>

Thanks for the info on the thermostat temperature threshold. The 32 degree or lower requirement would explain why I could not get the defrost cycle to force itself on with the back panel removed from the freezer. Yes, I believe once the thermostat is cold enough it is working as it should and the heater is coming on when I force a defrost cycle.