How to Test a Refrigerator Thermostat

If your edibles are too warm or start freezing, when they should not, or if there is frosting inside, then the refrigerator thermostat may be the cause. Knowing how to handle such situations is quite handy.
This article contains a step-by-step guide for testing and resetting your thermostat and other solutions for the thermostat problem.

Step-by-step Guide

How to Test a Refrigerator Thermostat 1

Check the thermostat setting

This is the first thing you should check. If your edibles inside the fridge are being frozen, then the thermostat was set to high level. If the edibles are being spoiled too fast, then the thermostat is at too low level.

Access the thermostat

If there is nothing wrong with your thermostat on the face of it, but the temperature is not stable, then you should get a good access to your thermostat.
Power off and unplug your fridge, then remove everything around the thermostat. You should be able to work comfortably with it.
You may need a flashlight, because it would be dark inside the fridge (remember, the fridge must be unplugged).
If there is a plastic cover over the thermostat, then remove that cover. You may also need to remove the thermostat dial too.

Use a multimeter

How to Test a Refrigerator Thermostat Use a multimeter

You will need multimeter for this step.
Set the thermostat to the coldest level. There are two lead wires attached – remove them.
Set your multimeter to lowest value at resistance measurement section or to continuity check mode (when it beeps). Then place proves on each terminal of the thermostat.
The multimeter should beep and/or display value around zero ohm. If it does not beep or the resistance is above zero, then you need to replace your thermostat.

Test your freezer again

If in the previous test the multimeter displayed zero value, then your thermostat may be working fine.
Remove the thermostat completely and turn it to the warmest setting. After that, install it back inside and power on your refrigerator for 30 minutes.
Then power off it again, remove the thermostat and probe the terminals on it.
The multimeter should display infinity, or should not beep, depending on how you set your multimeter. If it does not then the thermostat is faulty, you must replace it.
But if it is working fine, install it back inside. You should check for other causes of the refrigerator’s malfunction.
The evaporator coils may be clogged or something wrong is with the condenser.

Conclusion

The first thing to check is your thermostat inside your refrigerator, if there is an unexpected temperature change.
Make sure you’ve powered down your refrigerator to be safe while working with electrical wires and equipment.
You may contact the manufacturer about getting a new thermostat.
Do it, if you’re handy with repairing kitchen appliances by yourself, or call a professional, if you don’t.

Testing a Refrigerator Thermostat – FAQ

What is the refrigerator thermostat for?

The thermostat regulates the temperature inside your refrigerator. It powers the cooling compressor on to cool the fridge down. And when the fridge is cold enough, it powers the compressor off.
If the compressor was running all the time, then everything inside would freeze. You should set the temperature to the warmer level if something inside was frozen. Or set the thermostat to the colder level, if the edibles get spoiled too fast.

How does the thermostat work?

The thermostat controls the refrigerator’s cooling system. It maintains the electricity flow to the cooling compressor.
When it is too cold, the thermostat disengages and powers down the cooling compressor. When it is too hot, then the thermostat switches the compressor back on. There may be a bimetallic strip, that changes it’s shape because of temperature changes and engages or disengages electrical contacts inside your thermostat. Or there is a gas chamber inside and the gas pushes a piston, that engages/disengages a microswitch inside.

Why my refrigerator thermostat failed?

How to Test a Refrigerator Thermostat Clean Contacts

The thermostat may loose its gas because of a hole in the gas tube. The gas inside expands, when it’s warm, and the thermostat powers the compressor on. If there is no gas, then the thermostat would never power the compressor on.
There also may be a wiring problem. The contacts on the thermostat my corrode or the wires may become damaged somehow. You may try to clean the contacts.

How to check if the thermostat is malfunctioning?

The fridge is too warm: The thermostat malfunction may cause that.
Or the fridge is too cold: If it is colder, than usual, than the thermostat does not power the compressor off. Also, a possible thermostat malfunction.
The fridge does not maintain stable temperature: The temperature should be in range between 32F and 40F. If the temperature fluctuates too much, then the thermostat is most likely the cause.

How to check my thermostat?

Check if the fridge is powered on and a circuit breaker for it. Check the fridge fuses. Replace, if appropriate. Check the fridge’s power cord.
Remove the thermostat cover, replace the batteries, if there are batteries inside.
And read your owner’s manual, of course.

How to reset my refrigerator thermostat?

Check the refrigerator power cord and disconnect it. The refrigerator’s cooling system might produce a knocking noise, but it is fine. Leave the refrigerator unplugged for some time.
Turn off the controls for freezer and refrigerator itself (to OFF or to 0). Power on your refrigerator. Set the thermostat to the setting you need and wait for 24 hours for temperature to settle.
If the temperature is not at the desired level, then the refrigerator may need repair. Call a professional, if you can’t do it yourself.

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