The thermostat, or on newer fridges the temperature sensor and control board, tells the compressor when to start and stop. When it fails, the fridge can run too warm, too cold or swing between the two. Because other faults cause similar symptoms, it helps to know what a faulty thermostat actually looks like.
Faulty Fridge Thermostat Symptoms: The Short Answer
The main signs of a faulty fridge thermostat are the fridge not getting cold enough, the fridge freezing food, temperatures swinging up and down, the compressor running non-stop or not starting at all, and no change when you adjust the dial or setting. Before replacing a thermostat, rule out dirty coils, blocked vents, worn seals and defrost faults, which cause similar problems.
6 Signs Your Fridge Thermostat May Be Faulty
1. The fridge is not cold enough
If the thermostat does not call for cooling when it should, the compressor stays off and the fridge warms up. Food spoils faster and drinks are never quite cold.
2. The fridge is freezing food
A thermostat stuck closed keeps the compressor running, so the fridge gets colder and colder. Lettuce, milk and eggs start to freeze. Food stored in front of the cold air vent can freeze for other reasons, so check that first.
3. Temperatures swing up and down
A thermostat that switches erratically can cause large temperature swings. You may notice condensation, partly frozen items one day and warm items the next.
4. The compressor runs constantly or not at all
If the compressor never stops, or never starts, the thermostat or control system may not be switching it properly. Our guide on why a fridge runs all the time covers other causes.
5. Adjusting the setting makes no difference
Turn the dial or setting to its coldest position. On a mechanical thermostat you should hear a click and the compressor should start. If nothing happens, the thermostat may be faulty.
6. Broken dial or control
A cracked knob or damaged control panel can stop you setting the temperature correctly, and may hide a damaged thermostat behind it.
Noticing these symptoms? Call Ace Fridge Repairs on 0452 462 556 to have the thermostat and controls tested.
Other Causes That Look Like a Thermostat Fault
- dirty condenser coils or a failed condenser fan
- blocked vents or an overpacked fridge
- worn door seals
- an iced-up evaporator from a defrost fault
- a faulty evaporator fan
- a failing compressor or start relay
Our guide on why a fridge is not cooling explains each of these.
What You Can Check at Home
- Put a thermometer in a glass of water in the middle of the fridge and read it after a few hours.
- Compare the reading with the setting. A fridge section should generally sit around 3 to 5 degrees Celsius.
- Adjust the setting one step and check again after 12 to 24 hours.
- Clean the condenser coils with the fridge switched off at the wall.
- Make sure the vents are clear and the seals close properly.
Our step-by-step guide on how to reset a fridge thermostat explains how to reset and adjust mechanical and digital controls.
How a Technician Tests the Thermostat
A technician checks the thermostat or sensor against a calibrated thermometer, tests whether it switches at the right temperatures, checks sensor resistance on electronic models, and confirms the control board is responding correctly. Replacing thermostats, sensors and boards involves electrical work and should be done by a qualified technician.
Thermostat Repairs Across Sydney
Ace Fridge Repairs repairs thermostats, sensors and control boards for households and businesses across Greater Sydney, including Blacktown, Campbelltown, Parramatta and Potts Point. We are based at 93B Pagoda Crescent, Quakers Hill NSW 2763, and all repairs carry a 12-month warranty on parts and labour.
For residential or commercial fridge repairs, call 0452 462 556, 24/7.
Frequently Asked Questions
How do I know if my fridge thermostat is bad?
Common signs include a fridge that is too warm or freezing food, temperatures swinging, the compressor running constantly or not starting, and no response when you change the setting.
Can a faulty thermostat make a fridge freeze food?
Yes. A thermostat stuck closed keeps the compressor running, making the fridge colder than intended.
Can I replace a fridge thermostat myself?
Thermostat and sensor replacement involves electrical connections and should be done by a qualified technician.
What else can cause fridge temperature problems?
Dirty condenser coils, blocked vents, worn seals, defrost faults, fan failures and compressor problems can all cause similar symptoms.