Compressors pressurise refrigerant in an air conditioning (AC) system and pass it onto the evaporator to cool a vehicle's interior. You can find a cheap compressor to replace your broken one with Car Parts 4 Less.
The simplest way to describe a compressor is that it is the part of the AC system that begins the process of turning liquid refrigerant into cool air for a vehicle. Without it, the whole AC system can fail and your car or van - and you and your passengers - will be deprived of cooler temperatures. They do not tend to fail very often since they generally experience infrequent use during the colder months in most vehicles, but when they do go out on you, they are cheap enough to replace. A lack of cool air from the vents is usually the first sign of a faltering compressor, but be sure to check the whole AC system before purchasing a replacement; the fault may be due to a broken evaporator instead.