Will a freezer work properly if it is very cold or hot in my garage?

It will, but you must ensure the temperature is set properly. Temperatures should not go below 40°F or hotter than 100°F for the freezer to work efficiently. If temperatures are lower than 40°F your thermostat may not allow the appliance to turn on. The warmer the ambient temperature is (above 100°F), the more the appliance will run, and will be less efficient.