If your defrost system isn’t working correctly, frost can accumulate on the inside back wall of the freezer and block cool air from reaching the fridge. If your refrigerator has a forced defrost mode, you will need to test if your defrost heater turns.
If your heater heats up the frost will start to melt. If it doesn’t work, check the continuity through the defrost heater circuit from the electronic control board. Drop the control panel down to access the electronic control board.
To inspect the defrost heater circuit, the fridge temperature needs to be below 46 degrees. If its above 46 degrees, plug your refrigerator back in to bring the temperature back down. For safety’s sake, always make sure the refrigerator is unplugged before you check continuity. Check the thermistor resistance next.
If your current thermistor checks okay, you’ll probably ought to replace the electric control board.
Check the defrost heater and replace it if you can see it is damaged. Even if your defrost heater doesn’t seem to be damaged it could be broken, inspect the continuity using a multi-meter.
If your defrost heater is working, check out your bi-metal thermostat for continuity. If your meter reads close to actually zero ohms then you have continuity. Replace your defrost bi-metal if it’s electrically open. Winnipeg Appliance Repair can troubleshoot and repair all your refrigerator repair defrost problems.