Air regulators, commonly found on compressors, function as a metering device. They reduce downstream air pressure by using a valve or pin, along with a spring and sealed seat. Regulators routinely have an air gauge attached to them that can be adjusted manually by a knob, or have a fixed nut to monitor the set-point downstream flow. Some air regulators have an additional tank pressure gauge. Air regulators have quick-release couplers and pressure lines attached to them which feed air tools and other hardware. Troubleshooting an air regulator only requires a few steps and basic tools.
Check to see if the air source, usually a compressor tank, has adequate pressured air in it. Read the pressure on the air regular gauge to see if the needle points to a number on the gauge represented in pounds per square inch.
Check the compressor tank gauge for a reading. Both gauges should match pressure readings. If both gauges read zero, but you know you just filled the tank, press the release Schrader valve on the tank and listen for escaping air. If no air escapes, turn the compressor on and refill the tank. Make sure you hear no hissing sounds coming form the coupler joint at the air regulator, or the air regulator screw-in flange.
Look at the adjusting knob (or fixed nut) on the air regulator. It needs to be set according to your manufacture's specifications. Look up the setting mark in your operator's manual and turn the knob to the appropriate limit line mark on the regulator flange. If it has an adjustable nut, use an end wrench to open the nut so that air can enter the regulator from the tank. Some air regulator valves might not have an indicator mark, but need only be turned counterclockwise to open them.
Look for any bends or kinks in the pressure hose leading from the air regular to the end of the accessory hose end. Inspect the area just behind the quick release coupler joints for folds in the high-pressure hose. Replace the hose if it has a bloated appearance, or has a deep groove near the coupler joints.
Release the tank air pressure at the tank Shrader valve by pushing in the valve pin in with a paper clip. Disconnect the quick-release coupler at the air regulator fitting. Spray the interior of the air regulator coupler fitting with penetrating oil and push a paper clip end inside and depress the ball check valve several times.
Respray the coupler interior and push it back on. Spray penetrating oil in the coupler at the opposite end of the hose. depress the ball check valve several times (if equipped with one) with a paper clip. Respray the coupler interior with penetrating oil.
Make sure the tank has been depressurized at the Shrader valve. Use an end wrench to remove the air regulator base nut or stud bolt with an end wrench. Spray penetrating oil inside the air regulator valve fitting and work a paper clip back and forth inside the fitting.
Depress the spring valve several times. Wrap plumber's tap around the air regulator screw fitting and screw it back into the tank flange with the wrench. Turn the compressor on and fill up the tank to the operator's specified pounds-per-square inch.
Check the reading on the air regulator gauge and the tank gauge. If they match, hook up an air tool to the quick-release coupler on the end of the air supply hose. Pull the trigger to turn the tool on. If the tool works, you have set the adjustment correctly and unblocked the regulator. If the tank gauge reads full, but the regulator gauge does not register and no air passes through the regulator valve, then you must replace the air regulator.