This step-by-step repair guide gives instructions for replacing the check valve on an air compressor. The check valve stops compressed air from flowing back into the pump from the tank. If the check valve is stuck open, high air pressure from the tank flows back into the pump head. The high pressure in the pump head won’t allow the piston to move, and the motor can’t start. Replace the check valve with the manufacturer-approved replacement part.
Use these steps to replace the check valve on common Craftsman, Dewalt and Devilbiss air compressors.
This video explains how to replace the check valve on an air compressor.
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.
Drain the air tank.
Disconnect the pressure switch tube
Unscrew the pressure switch tube fitting and disconnect the pressure switch tube from the check valve.
Disconnect the pressure switch tube.
Disconnect the outlet pressure tube
Unscrew the outlet tube fitting and disconnect the outlet tube from the check valve.
Disconnect the outlet tube from the check valve.
Remove the check valve
Unscrew the check valve and remove it from the tank.
Unscrew the check valve.
Install the new check valve
Thread the new check valve into the tank.
Tighten the check valve and align the fitting to connect the pressure switch tube.
Install the new check valve.
Reconnect the outlet tube
Reinstall the outlet tube on the check valve.
Reinstall the outlet tube.
Reconnect the pressure switch tube
Reinstall the pressure switch tube on the check valve.
Reinstall the pressure switch tube.
Plug the compressor back in.
Plug the compressor in.
If the air compressor won't fill the tank with compressed air, rebuild the pump using these steps in about 45 minutes.
You can replace a broken air compressor pressure switch in about 45 minutes.
These answers to common questions can help you make the most of your air compressor.
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