Gemini said
SAFETY DISCLAIMER: Working with appliances involves risk of electric shock and mechanical injury. Always disconnect the power before attempting repairs. If you are unsure, consult a certified professional.
Master Fridge-Freezer Troubleshooting: Control Board & Thermostat Issues
If your refrigerator is acting up, the culprit is often the control board or the thermostat. Understanding how these components interact is the first step toward a successful DIY repair.
Key Diagnostic Tips:
Temperature Fluctuations: If the fridge is too cold or too warm, the thermostat or thermistor may be failing to send signals to the control board.
Total Power Loss: A completely unresponsive unit often points to a blown fuse or a faulty main control board.
Constant Running: If the compressor never stops, it could be a stuck relay on the control board or a thermostat that no longer detects the set temperature.
Improved Repair Strategy:
Safety First: Unplug the appliance and wait 5 minutes for capacitors to discharge.
Accessing the Board: Most control boards are located behind a rear panel or inside the top console.
Visual Inspection: Look for "burnt" spots or bulging capacitors on the circuit board.
Testing: Use a multimeter to check for continuity on the thermostat. No continuity usually means the part needs replacement.
Electromechanical thermostatic control
The older well used thermostats with a long thin phial tube filled with gas, as this gas expands with temperature it will operate the on-off switch to control the refrigeration system. They are just simple on and off controls and cycle the temperature as close to a set temperature as possible but can never be very accurate but they are very simple in operation and in fault finding. They usually fail on so the cooling never stops and over freezing occurs. If it fails off obviously no cooling will take place and the fridge will not cool and food will spoil.
Thermostats turn the compressor on and off and try to hold the temperature set inside the fridge freezer cavity this on off cycling is not very efficient and at best will only hold the temperature to around 10% either side. So a thermostat set at 3 degree could turn off at 2 degrees and back on at 4 degrees.
Electronic control
Uses an electronic control board, chips and programmed software to control the temperature inside the fridge freezer cavity. A thermistor inside the cavity being cool senses the temperature which signals the control board of the temperature this is then compared to the set temperature of the unit. This information is then used to control the refrigeration system be in on-off control of a standard compressor or variable control of an invertor ran compressor. These control units are also programmed to self monitor and give fault codes if anything goes wrong. These systems are a lot more accurate but this traded of by being more complex and harder to fault find.
See video below of how to test both thermostats and thermistors
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