How to Test Whirlpool Refrigerator Defrost Thermostat-Bi-Metal

In order to complete this job you will need the following tools:

Needle nose pliers

phillips screwdriver

1/4″ nut driver

Ohm meter/voltage meter

Please Note: The process for changing a defrost heating element applies to all three styles of refrigerators. The three styles are, side by sides, top freezer mounts, and bottom freezer mounts.

The very first thing that you need to do before you begin your installation is to disconnect the power supply to your appliance. Sometimes there can become a build up of frost on the evaporator panel. If this has occurred on your evaporator panel, you will need to defrost it first. The preferred method is with a hairdryer. DO NOT use a heat gun. It will give off too much heat, and could warp and deform your plastic liner. Once you have defrosted it to the point that you can see the screws, you can stop defrosting. Now you should be able to remove the screws along with the evaporator panel.

After the evaporator panel is removed, you will need to defrost the evaporator as well so that you can locate the defrost thermostat.

Note: If you have a top or bottom mount freezer that contains your icemaker, it will need to be removed as well. After you have removed the evaporator panel, you also have to defrost the evaporator. You must do this so that you can locate your defrost heating element. It will be a black cylinder heater, or a glass cylinder that contains a coiled wire inside of it. The glass tube style of defrost heating element is VERY FRAGILE, and if broken is very dangerous.

Note: Do not totally defrost the evaporator coils. You need the defrost bi-metal switch to stay cold. It needs to be cold in order for you to test it. The defrost bi-metal switch contact is closed when it is cold, and open when it is warm. You will find the defrost bi-metal switch fastened to the top right, or left corner of the evaporator coil.

Now that you have located the defrost bi-metal switch, now you need to locate the wire ends or wire harness and unplug them. Set the Ohm/Voltage meter to Ohm. Attach one lead to each of the wire ends, to test the bi-metal switch. If the meter reads zero on a digital Voltage meter, or if the needle moves to the right on standard Voltage meter, then your bi-metal switch is good. (If the bi-metal is still cold) If the meter reads one on a digital voltage meter, or the needle does not move on a standard voltage meter, then the bi-metal switch is bad and it will need to be replaced.

Once you have completed testing the defrost bi-metal switch, put the evaporator panel back on and you also need to reinstall the icemaker(If applicable) You have completed the job!

We know this is only a general idea on how to change the defrost thermostat Bi-Metal, but it should give you the most important points to be able to complete the job. If you still have any questions on this process, please feel free to contact our tech support. They will be standing by to take your calls, and help you in any way that they can.