Whether it is keeping food fresh or freezing your favourite ice cream, your freezer serves no purpose if the thermostat is not working. A damaged thermostat prevents you from regulating your freezer's temperature to ensure that it remains cold. Food becomes warm and goes bad, ice cream melts -- both are consequences of a damaged thermostat. While refrigerator models vary, replacing the thermostat is necessary if your freezer is not cooling.
Purchase a new freezer thermostat from a retail or appliance store. Locate the part you need using your fridge's model or serial number. Refer to your refrigerator's manual if you are not sure of the model and serial number.
Turn off your fridge and disconnect the plug from the unit. Depending on the type of refrigerator you are using, you can also turn off the fridge from the circuit breaker. Refer to your fridge's documentation if you are unsure of the location of the circuit breaker.
Locate your fridge's freezer thermostat. The thermostat is usually located in the freezer or bottom part of your refrigerator depending on the model. Check under the floor of your unit, or the back of your freezer. Some fridge models keep the thermostat in these locations.
Remove food, freezer shelves and icemaker parts in the way of the thermostat panel.
Remove the thermostat panel. Depending on your fridge model, the panel is held in place by either screws or clips. Remove the screws or clips with a screwdriver. If you are using an older refrigerator, remove plastic moulding to gain access to the freezer floor and then remove the thermostat panel.
Locate the two wires leading from the thermostat attached to terminals with slip-on connectors. Gently remove the wires from the terminals using needle-nosed pliers. Do not pull the wires because you risk damaging them.
Remove the thermostat gently. If it is secured in place with an additional screw or clip, remove it. Depending on your refrigerator model, remove the thermostat by squeezing it on the clip and pulling it up until it pops out.
Place your new thermostat in the compartment. Reconnect the wires and replace the panel. Plug your fridge back into the electrical socket and turn it on.
Consult a qualified appliance technician if you do not feel comfortable replacing your freezer thermostat.