Disconnect the refrigerator's power cord from the electrical outlet or shut off the power from your home's circuit breaker panel.
Locate your refrigerator's temperature control box. Consult your owner's manual if you are unable to find the box by looking inside the compartments. This control box is generally installed either in the freezer’s back or under the refrigerator’s floor. You may have to loosen a set of screws or clips to remove the control box cover.
Remove the existing thermostat, if applicable to your refrigerator. Pull the wires from the thermostat's terminals with needle-nose pliers, and then release the clamps or retaining clips holding it in place. Install the new thermostat in the same location. Connect the two wires coming from the refrigerator to the thermostat's terminals.
Put the control box cover back on and tighten the screws or clips. Restore the power to the refrigerator from the circuit breaker panel or plug the power cord back into the wall outlet.