The furnace that heats your home is sometimes referred to a heater, but the air conditioner you use to cool your house in summer is rarely called a "cooler." This is because an AC does more to the air in your house than cool it down. They also remove humidity, making your home much more comfortable in hot and humid weather.
The most important part of an air conditioner is an air compressor, which consists of a piston moving back and forth inside a container of air. Air is simultaneously heated and cooled on opposite ends of the device. The hot air is expelled outside and the cooler air is fanned into your house. The process also squeezes out some of the moisture, which drips away outside. Unfortunately, your furnace is not capable of adding moisture to the air it is heating, so we spend our winters applying lotion to the skin to keep it from cracking.