105-135 PSI Pressure Switch PS2020M - $54.41

Essentially the “brain” of the air compressor, the pressure switch senses the pressure in the tank and controls when the unit shuts on and off. All switches are preset for specific cut-on and cut-out pressures at the factory, so be sure to order the exact OEM part number your manual calls for, or make sure the specs are identical to your original if you do not have a part number to order by. The major brands are Furnas (Hubbell), SquareD, Condor and Huanli. Most have either a single port or four-port manifold to attach a safety relief valve, pressure gauge or an air regulator. Replace this if the unit doesn’t cut on and off at the specified pressures for your unit, if it leaks or if the copper contacts inside are corroded or burnt.