The Canadian Food Inspection Agency recommends that refrigerators be set at or below 4C (40F). Food kept above this temperature for two hours or more may grow pathogenic bacteria and should not be eaten. Use a refrigerator thermometer to routinely check the temperature of your appliance. Keep in mind that these thermometers can be notoriously inaccurate so if it gives you an unusual reading go buy another one to get a second opinion (usually cheaper than a repair call for a problem free fridge).