Many businesses, like collision repair shops, rely on industrial air compressors to operate the tools they use to fix cars damaged in an accident. If the air compressor breaks down, a collision shop can't get the work done they need to, and this can lead to unhappy customers and lost business opportunities. A major reason why an air compressor will stop running is because an electrical short will occur in the switch and the compressor won't turn on. If you have had a short in your air compressor and it won't start, here is how you can fix the pressure switch so you can get back to work.
You need to unplug the air compressor or, if it's hard-wired, turn off the circuit breaker before you start to work on the compressor since you'll be working on electrical parts. You should also discharge the pressurized air from the tank to prevent any accidents. To remove the pressurized air, pull the ring on the safety valve until all the air has been discharged.
Inspect the Pressure Switch
Remove the screw on the pressure cover and lift the cover off of the unit. Look at the wires to see if any of them are frayed and/or burned out at the end. If you see damage to the wires, it means the switch has a short in it and should be replaced. You should also replace the damaged wires going to the motor. Take a picture with your cell phone or digital camera to see how all the wires are connected to the switch and then remove them. You will refer to the picture as a guide when reconnecting the wires.
Replace the Pressure Switch
Take a wrench and unscrew the tank pressure gauge connected to the top of the switch. Set the tank pressure gauge aside. Unscrew and remove the fittings for pressure switch tubes for the check valve and pressure switch. Unscrew and remove the pressure regulator assembly and remove it. Unscrew the safety valve on the side of the switch and remove it. There is a nut-like assembly at the base of the switch. Take a wrench and turn the nut counterclockwise to unscrew the switch from the compressor.
Take some plumber's tape and put it on the threads of the new switch and screw it onto the compressor. Replace all the parts in the reverse order in which you took them off. Make sure you put plumber's tape on the threads of the pressure regulator, too. The threads for the hose fittings are self-sealing and you won't need plumber's tape when reconnecting the fittings.
You need to remove the screws on the cap of the motor and take it off. The wires from the switch are connected to a plate right behind the cover. Take a picture of these wires before you remove them.
Take the wires from the new cord and put them onto the plate in the motor in the same manner in which you took them off (refer to your picture). The wires will have different colors so you can tell which one goes where on the motor plate and on the pressure switch. Now, connect the other end of the cord to the new pressure switch using your picture as a guide. Replace the pressure switch cover once you have reconnected the wires.
Put the cover back on the pressure switch and turn the electric back on. Start the compressor to make sure it works well. Check out sites like http://www.compressor-pump.com for more information.