Air compressors drive many different types of tools and machines. Compressed air can be used to lift huge weights and drive large nails into lumber or concrete. A compressor that will not build lasting pressure is useless. Without the ability to control the flow and pressure of air, it cannot drive tools or run machines. There are two possible causes for a compressor that runs, but does not build up pressure. The limiter switch may need to be adjusted, or there is an air leak that needs to be fixed. If you find that your tank itself is damaged, consult professional help to prevent harmful tank explosions.
Disengage all tools and hoses. Turn the compressor on and spray a solution of soap and water over the connections between the air compressor and its fittings. Look for bubbles to appear in the solution, indicating an air leak. Turn the compressor off and pull the release valve, a plastic and metal valve with a pull ring in it, to release the pressure from the tank.
Remove any fittings that had bubbles around them. Turn the fitting counterclockwise with a wrench to remove it. Wrap Teflon around the threads of the fittings and re-thread them, tightening the fittings with the wrench by turning them clockwise.
Test the compressor to see if the pressure is sufficient. If not, remove the cover from the pressure-limiting switch and turn the upper limiting screw clockwise to tighten, raising the upper pressure limit, so that the tank can fill more fully. Use a screwdriver to turn the screw.
Bleed the water from the tank by turning the compressor on and allowing it to fill as much as possible. Locate the bleeder valve on the underside of the tank. Grip it with locking pliers and turn it counterclockwise to release the valve, allowing the condensation to be blown out with the air from the tank. Once the condensation stops dripping, turn the valve clockwise to close it. Charge and retest the compressor. See professional assistance for a compressor that does not respond to these steps.