May 1, 2015

How to replace an air compressor pressure switch

By Lyle Weischwill
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 replacement part.

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

Quick links
Tools required
Work gloves
Wrench set
Nut driver set
Thread-sealing tape
Repair difficulty
Time required
45 minutes or less
Repair difficulty
Time required
45 minutes or less
Replacing a pressure switch on an air compressor

This video explains how to replace the pressure switch on an air compressor.

Instructions

01.

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.

Unplug the power cord.

Unplug the power cord.

Drain the air tank.

Drain the air tank.

02.

Remove the tank pressure gauge

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

Remove the tank pressure gauge.

Remove the tank pressure gauge.

03.

Remove the pressure switch tube

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

Remove the pressure switch tube.

Disconnect the pressure switch tube.

Disconnect the pressure switch tube.

Unscrew the pressure switch tube fitting.

Unscrew the pressure switch tube fitting.

04.

Remove the pressure regulator assembly

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

Unscrew the pressure regulator assembly.

Unscrew the pressure regulator assembly.

05.

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.

Remove the pressure switch cover.

Remove the pressure switch cover.

Disconnect the black wires.

Disconnect the black wires.

Disconnect the green wires.

Disconnect the green wires.

Unscrew the safety valve.

Unscrew the safety valve.

Unscrew the pressure switch.

Unscrew the pressure switch.

06.

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.

Screw on the new pressure switch.

Screw on the new pressure switch.

Screw the safety valve on.

Screw the safety valve on.

Remove the new pressure switch cover.

Remove the new pressure switch cover.

Reconnect the wires.

Reconnect the wires.

Reinstall the pressure switch cover.

Reinstall the pressure switch cover.

07.

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.

Reinstall the pressure regulator.

Reinstall the pressure regulator.

08.

Reinstall the pressure switch tube

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

Tighten the fittings firmly.

Reconnect the pressure switch tube.

Reconnect the pressure switch tube.

Tighten the fittings firmly.

Tighten the fittings firmly.

09.

Reinstall the tank pressure gauge

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

Screw on the pressure gauge.

Screw on the pressure gauge.

10.

Restore power

Plug the air compressor into the electrical outlet.

Plug the compressor in.

Plug the compressor in.

Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.
Symptoms common to all air compressors

Choose a symptom to see related air compressor repairs.

Main causes: lack of electrical power, check valve failure, bad pressure switch
Main causes: rusted air tank, loose air tube fitting connections, bad check valve, leaky safety valve, bad tank drain valve
Main causes: bad safety valve, pressure switch failure
Main cause: faulty output air pressure regulator
Main causes: tank drain valve open or leaking air, leaky air tank, bad safety valve, worn pump seals, bad pump valve plate
Main cause: bad air tank pressure gauge
Main causes: loose air tube fitting connections, bad check valve, faulty safety valve, damaged or corroded air tank, bad air pump
Repair guides common to all air compressors

These step-by-step repair guides will help you safely fix what’s broken on your air compressor.

May 1, 2015
By Lyle Weischwill
How to rebuild an air compressor pump

If the air compressor won't fill the tank with compressed air, rebuild the pump using these steps in about 45 minutes.

Repair difficulty
Time required
 45 minutes or less
How to replace an air compressor pressure switch

You can replace a broken air compressor pressure switch in about 45 minutes.

Repair difficulty
Time required
 45 minutes or less
How to replace an air compressor check valve

You can replace a defective air compressor check valve in about 10 minutes.

Repair difficulty
Time required
 15 minutes or less
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