Air compressors pump high-pressure air to fill gas cylinders, to supply divers, to help in powering pneumatic HVAC control systems, and to power pneumatic tools. They can also be used for household applications and there are special air compressors for inflating tires.The compressor draws in air and creates a vacuum to reduce its volume. The vacuum pushes the air out of the chamber and into its storage tank. Once the storage tank reaches its maximum air pressure, the compressor turns off.The compressor will turn back on when the pressure drops below a specific number.