Bimetal Defrost Thermostat

Read on Internet that a warm freezer was caused by frost build up on the coils. Took of coil cover in freezer section and verified this. There were two possible sources, a bad Bimetal Defrost thermostat or a defrost timer. I did notice that the defrost thermostat top was bulging and suspected it was the problem. However, since my food was rotting, I did not have time to order the defrost timer if the thermostat was not the issue... so I purchased both parts. The only issue I had with installing is that the defrost thermostat wires ended up going through a tight sealed opening in that back wall with cooling lines. At the end of the new defrost thermostat there was a connector that would not fit through the opening. After taking off the back cover panels, I discovered that the wires were just hanging out the back unconnected with a label of "Factory Test". So, I just cut them and pulled the wire out. Then I did not bother to run the new defrost thermostat wires through and just tied them up with supplied zip tie. Problem was fixed... never needed to install the defrost timer kit.

First let me say the appliance guy said I needed to replace the whole freezer coils within the freezer part but the unit after using a hair dryer would work fine for two weeks then freeze up again. His conclusion of leaking refrigerant did not make sense, nor the noting of uneven freezing, so I figured I would take a chance on logic. The worst part was unloading the refrig and throwing away a boat load of food. Anyway once I removed the back panel that reveals where the defrost thermostat is I simply followed the wires by disconnecting the old and attaching the new until I got to the last two - brown and orange which actually go behind the defrost heater element and disappear below the fan. I cut both & used the adapter peice did a crimp - done. The timer took 5 minutes. Its working fine and cooling fabulously! I wanted to get past the two week point it is now in its 4th and doing fine. By he way the cams, thanks to your video took 10 minutes. Very satisfied and will recommend DIY because everyone else seems to want to retire on my dime!

suspected the defrost heater, as fridge always tripped when defrost timer (orange knob behind bottom front grill) was at 3 o clock. Undid the freezer back plate, disconnected heater, rotated knob to 3 o'clock, no trip. ordered new heater and thermostat. can pull cooling coil outward(be gentle) Need needle nose plier to remove clips holding heater in place.
replaced heater, also thermostat for good measure.
Voila!!!

I replaced the defrost timer, and then the defrost thermostat. I diagnosed these two items because it would get cold/freeze great for about 12-24 hours and then would start to warm back up. I pulled the cover off that covers the evaporator coil and found it to be frosted up. This told me that the defrost timer probably wasn't working properly. Decided to replace the defrost thermostat while I was in there as a precaution. It was much much cheaper than having to replace a side by side!!

Unplugged fridge. Removed the lower panel inside freezer. Cut off wires to Bimetal Defrost Thermostat and used wire nuts to install new one. Too much bother to replace everything they gave with the thermostat. Two wirenuts are fine.

I first though the Fan was the problem, but read here about the thermostat. I think moisture gets into the thermostat and rusts the wires and pushes out on the cap causing falure. Someone could attempt to resolder some wires to it after removing the cap. Then re-seal.

As a temp repair you can wire nut the wires together. The only problem is when it goes into defrost mode it will circulate warm air, but it works until the new thermostat arrives.

The defrost circut stopped working which caused the coils to frost over stopping the blower and freezing the water line. Take everything out of the freezer, remove lower back pannel held in by around 8 screws inside the freezer. The thermostat was attached to the upper right coil. It clips on to the coil. Wires attach to the fan and defrost heater. A pair of wires runs out through a hole. These wires are to measure thermostat. It will read 0 ohms when frozen. Rremove and replace the thermostat. The defrost heater should read around 25 ohms. Remove the bottom grill. It pops off. The box in the middle houses the defrost timer. Remove the 2 screws holding the box to the chasis and then remove the defrost timer screws... Before buttoning everythigng up, plug the fridge in to the power and wait for about an hour. The fan in the freezer just above the coils should be running and circulating cool air through the fridge and freezer. Depending on how long your freezer was unplugged, the water should be thawed enough to dispense water again.

Remove sheet metal cover inside freezer lower half at back to expose the coils.
Cut the zip-tie holding the thermostat wires.
Un-clip bi-metal thermostat from metal coolant line. Disconnect the thermostat electrical connections (use pliers if difficult).
Connect the new thermostat wires.
Clip the new thermostat to the coolant line.
zip-tie the wires again.
replace the sheet metal cover.

It takes about 10 minutes for the thermostat to turn on the freezer fan after power-on if the freezer is room temperature.

Did diagnostic troubleshoot on web. Checked to make sure heater was defrosting ( it was ) .Checked evaporator fan was working ( it was ) . Determined the Thermostat was defective , removed stat and checked resistance it was shot. ordered new one reattached wiring with butt splices ( two wires ) .refrigerator works better than before had to turn it down . easy fix cost $42( incl. shipping ) compared to $?? for repair guy or new fridge .Wifes happy so Im happy life is cool again !!