How to replace an air compressor pressure switch

This DIY repair guide explains how to replace the pressure switch on an air compressor. The pressure switch starts the pump motor as the tank empties and pressure drops to the cut-in pressure; the switch stops the motor when tank reaches the cut-out pressure.

Over time, the pressure switch wears out. If the pressure switch won’t start the pump when tank pressure drops below the cut-in pressure or won’t stop the pump when the tank reaches the cut-out pressure, replace the pressure switch with the manufacturer-approved air compressor part.

This procedure works on common Craftsman, Devilbiss, Dewalt, Campbell Hausfeld and Porter Cable air compressors.

Instructions

1. Shut off the electricity and drain the air tank

Unplug the air compressor’s power cord from the wall outlet.

Pull the ring on the safety valve to drain all air pressure from the tank. Wear work gloves to protect your hands.

2. Remove the tank pressure gauge

Unscrew the tank pressure gauge and remove it from the pressure switch.

3. Remove the pressure switch tube

Unscrew the pressure switch tube fittings from the check valve and pressure switch.

Remove the pressure switch tube.

4. Remove the pressure regulator assembly

Unscrew the pressure regulator assembly and remove it from the pressure switch.

5. Remove the pressure switch

Remove the pressure switch cover.

Take a digital photo of the wires connected to the pressure switch for use later when reconnecting wires.

Disconnect the 2 black wires from the pressure switch.

Disconnect the 2 green wires from the pressure switch.

Pull the 2 power cord strain reliefs off the pressure switch.

Unscrew the safety valve and remove it from the pressure switch.

Unscrew the pressure switch assembly from the pipe connected to the tank.

6. Install the new pressure switch

Apply thread-sealing tape to the tank pipe.

Screw the new pressure switch onto the tank pipe.

Tighten the pressure switch and align the check valve tube fitting.

Apply thread-sealing tape to the threads of the safety valve.

Screw the safety valve into the new pressure switch and tighten firmly.

Remove the new pressure switch cover.

Using your digital photo as a reference, connect the wires to the new pressure switch.

Insert the power cord strain relief into the strain relief bracket.

Reinstall the pressure switch cover.

7. Reinstall the pressure regulator

Apply thread-sealing tape to the pressure regulator connecting pipe threads.

Screw the pressure regulator and pipe into the new pressure switch and tighten firmly with the tank gauge fitting facing up.

8. Reinstall the pressure switch tube

Reconnect the pressure switch tube to the check valve and the pressure switch.

Tighten the fittings firmly.

9. Reinstall the tank pressure gauge

Screw the pressure gauge onto the new pressure switch and tighten the gauge firmly.

10. Restore power

Plug the air compressor into the electrical outlet.