Bimetal Defrost Thermostat. This clip-on thermostat will sense the temperature increase in the evaporator during the defrost cycle and will cycle the defrost heater off after the ice or frost is melted.
http://www.partselect.com/PS11742474-Whirlpool-WP4387503-Bimetal-Defrost-Thermostat.htm
Whirlpool W10165425 Defrost Bimetal for Refrigerator. Works with the following model: Whirlpool EB9FVHXVQ00, Whirlpool EB9FVHLVS00, Whirlpool EB9FVHRVS00, Whirlpool EB9FVHXVB00, Whirlpool GB2SHDXPB02.
https://www.amazon.com/Whirlpool-W10165425-Defrost-Bimetal-Refrigerator/dp/B005AR9FJU
The most common control is a mechanical defrost timer which is a motorized device that opens and closes several electrical contacts. Each contact can be thought of as a simple light switch but instead of a light, one connects the defrost heater circuit, another connects the cooling system.
http://www.appliance411.com/faq/howdefrostworks.shtml
This manufacturer-approved defrost bi-metal thermostat (part number WP67003426) is for refrigerators. Defrost bi-metal thermostat WP67003426 protects the evaporator from overheating during the defrost cycle. Safely store any food that could deteriorate while the power is off. Unplug the refrigerator before installing this part. Wear work gloves to protect your hands.
http://www.searspartsdirect.com/part-number/67003426/0046/464.html
There are many separate components in a refrigerator's defrost system that must work in concert for a frost free system to work properly. We will attempt to explain the workings using simplified electrical schematics. The heart of the defrost system is the defrost control.
http://www.appliance411.com/faq/howdefrostworks.shtml
By Amazon Customer on March 14, 2014. Verified Purchase. I ordered this defrost thermostat for my refrigerator, when it arrived it was identical to the old one. I knew from past experience that you needed to check a new defrost thermostat as there was a chance it was defective.
https://www.amazon.com/Whirlpool-W10165425-Defrost-Bimetal-Refrigerator/dp/B005AR9FJU
Manufacturer Part Number WP4387503. Manufactured by Whirlpool. This clip-on thermostat will sense the temperature increase in the evaporator during the defrost cycle and will cycle the defrost heater off after the ice or frost is melted.
http://www.partselect.com/PS11742474-Whirlpool-WP4387503-Bimetal-Defrost-Thermostat.htm
The defrost timer eventually switches into defrost mode and supplies power to the defrost heater(s) to melt any frost that has accumulated on the evaporator (cooling) coil. The cold control contacts remain closed but since the defrost timer is no longer feeding power to that circuit, the compressor does not run.
http://www.appliance411.com/faq/howdefrostworks.shtml
Received the new thermostat, checked it, checked good, refrigerator is no more problem. By the was Amazon was the lowest price, BY FAR, for the part. I must stress that the part was not an aftermarket clone it was OEM. The fault was not with Amazon in any way.
https://www.amazon.com/Whirlpool-W10165425-Defrost-Bimetal-Refrigerator/dp/B005AR9FJU
During the cooling mode, the defrost timer closes a contact to the compressor circuit so it will run. The circuit to the defrost heater is open. While in this mode, the thermostat (a.k.a. cold control) cycles the compressor and fan motors on and off to maintain an appropriate temperature.
http://www.appliance411.com/faq/howdefrostworks.shtml
what is bi-metal on refrigerator
The Bi-metal  is thermostat WP67003426 protects the evaporator from overheating during the defrost cycle.