How to Troubleshoot & Replace Whirlpool AP6005218 / WP10442411 Refrigerator Defrost Thermostat

Could have been three failures: timer, defrost heater, or thermostat. Testing the thermostat showed that it was the problem. Replaced defrost thermostat. Note: the replacement thermostat had a different connector from the original, so I had to cut the new connector off and splice the original connector onto the wire. 

Replace the defrost timer 

Replaced the defrost thermostat. Part received from Appliance Parts Pros had a different (than the OEM) type of connector on one of the leads, as I had anticipated. Simply removed connectors from thermostat lead and the wire from the refrigerator harness, stripped the wires and connected them with a wire nut. All that was fairly easy, except for the difficulty accessing the back of the freezer section. Also experienced some difficult aligning the holes in the removable panel with the holes in the mounting brackets, again exacerbated by the difficult access. Nonetheless, the project appears to be a success in that I have no visible frost on access panel after 3 weeks of operation. That may not be the most thorough test since it is not particularly humid this time of year. 

Was really pleased with the fast shipping, but when the part came I was disappointed to find that the terminal connections were not the same on one side of my new thermostat so I had to go to the store to change the connector. otherwise it took me 10 mins to install and put my back plate and drawer back in. 

Having searched the symptoms, the diagnosis was a bad defrost thermostat. I wanted a repair shop to just come and take care of it, but they were backlogged to due to a week of snow and cold temperatures. So I gave AppliancePartsPros.com a chance. Undoing the screws in the freezer was easy. After a little work with a heat-gun to get the iced up coils clear, the thermostat was easy to identify, and un-clip. The connectors did not match exactly, but the wires were properly coded. So I clipped the connectors and used wire-nuts and electrical tape to make the connections. It took some muscle to get the clip over the pipe, but it was easy enough. I replaced the machine screws on the access panels, reloaded the freezer, and plugged it in. So far so good. Hopefully that does it. 

Replaced defrost timer and defrost thermostat. 

Replaced the defrost thermostat 

Removed icemaker and rear interior freezer cover. Defrosted coils and old thermostat with hair dryer. Replaced thermostat. Original brown wire used banana plug, not spade connector, so I used a butt splice with heat shrink. 

Replaced defrost thermostat. Just watch the video! 

My freezer was working fine but the fridge section was warm. Also, there was no air flowing into the fridge section. I replaced the defrost thermostat. for this model 596.69279991. To replace the thermostat you need to open the freezer section. when you open the freezer door, you will see screws at the back. Unscrew them and take the back plate out. The defrost thermostat is on the right-hand side. After I replaced it, the fridge is working like a charm.