How to Test Whirlpool Refrigerator Defrost Thermostat, Bi-Metal

To perform this work 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 refrigerator styles. The three styles are Side by Side Top Freezer Mounts and Bottom Freezer Mounts.

The first thing to do before starting the installation is to disconnect the power supply of your device. Sometimes frost can build up on the evaporator panel. If this has happened to your evaporator panel, you will need to defrost it first. The preferred method is with a hair dryer. DO NOT use a heat gun. It will give off too much heat and could warp and warp the plastic lining. Once you have thawed it to the point where you can see the screws, you can stop thawing. You should now be able to remove the screws along with the evaporator panel.

After removing the evaporator panel, you will also need to defrost the evaporator in order to locate the defrost thermostat.

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

Note: Do not completely defrost evaporator coils. You need the bi-metal defrost switch to keep cool. It has to be cold so you can taste it. The bimetallic defrost switch contact closes when cold and opens when hot. You will find the bi-metallic defrost switch attached to the upper right or left corner of the evaporator coil.

Now that you have located the bimetallic defrost switch, you need to locate the ends of the wires or harness and unplug them. Set the ohm/voltage meter to ohms. Attach a lead to each of the cable ends to test the bimetallic switch. If the meter reads zero on a digital volt meter, or if the needle moves to the right on a standard volt meter, then your bimetallic switch is good. (If the bimetal is still cold) If the meter reads one on a digital voltmeter, or the needle does not move on a standard voltmeter, then the bimetallic switch is bad and will need to be replaced.

Once you have completed the bi-metal defrost switch test, replace the evaporator panel and you should also reinstall the icemaker (if applicable). You have completed the job!

We realize this is just a general idea on how to change your Bi-Metal defrost thermostat, but it should give you the most important points to get the job done. If you still have any questions about this process, feel free to contact our technical support. They will be ready to take your calls and help you in any way they can.