Heater

A refrigerator will by design heat up a room.

To make something colder, you need to find a way to remove the heat. In the case of refrigerators, this can be done by pumping the hotter air out until you're left with cold air.

This is also why a refrigerator can by design never cool down a room.

An easy way to prove this, is by leaving the refrigerator door open. Over an extended period of time, you'll never see the temperature of the room lower (except maybe during the initial opening).