Good, it only needs to work. Dead on accurate is not important. This is what to do. Unplug the freezer. Defrost the coils behind that wall inside the freezer. You should find those coils completely blocked with frost. The air cannot flow.
Running along the bottom of those coils you will find the defrost heater mounted up very close. Follow the wires from the heater. One wire will connect to another part at the top of the coils that is the defrost thermostat.
Disconnect the heater wires. Set your meter to any ohm setting. Put one probe to each wire end for the heater. If the meter shows continuity the heater is good. None then replace the heater.
The thermostat the heater was connected to needs to be cold, so make everything safe and get the thermostat good and cold. Same test. Continuity is good, none and its bad. Replace that thermostat.
If you find both of those good then replace the control. I have an image for it but I cannot tell on the diagram exactly where it is but I do have a picture of it below. This part is usually located to the rear or underneath.
I have to go pickup someone, it will take me about 15 minutes. If you have questions I will not be long and if you do not please leave a rating.
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