For Whats its Worth ....

Over the last few days, I have been trouble shooting a defrost issue on my side by side Whirlpool refrigerator. The common failures here are the bi-metal defrost thermostat, the defrost heater and the defrost heater control board.

This exercise and associated research made me realize that if you replace your refrigerator or if you are purchasing a used coach, make sure that as many parts as possible are accessible from the FRONT. There is really no room on a no slide coach to pull the refrigerator out and easily access parts that are on the rear. Several youtube videos of other refrigerators showed control boards etc. on the back side. Fortunately for me, all three of these parts are accessible from the front on mine.

Also, one reputable parts site said that the bi-metal defrost thermostat behaves like a thermistor. You check it by measuring resistance at room temp and in ice water. At least for me, this was NOT correct and delayed the diagnosis. My bi-metal tstat works like a switch. It is open at 45 degrees F (55.6 kohms) and closed (0 ohms) at well below freezing. There is a code on the bi-metal that shows the open and closed temperature (sometimes in degrees C.) The first number is the open temperature and the second number has to be subtracted from the first to get the close temperature. The close temperature is in the single digits F. and is way too cold to be activated in ice water. It will only activate in a freezer or perhaps with a can of freeze spray, etc.

I ran into similar issues trying to get information on resistance of the defrost heating element. Some said that it could be 0 to 50 ohms, some said 21 ohms to 27 ohms, a manufacturer rep said it had to be 45 ohms period or it was bad. Mine measured 27 which fit 2 of the 3 sources so I assumed it was fine. My assumption is that if it fails, it will fail full open.

In the end I sprung for the control board. When I pulled it out, there was a burned spot on the board and my change filter light came back on ... so fingers crossed, problem solved.