My air compressor is shutdown due to low unload sump pressure and I noticed that while unloading the air which is coming out from the blowdown selnoid valve is very weak and sump press below 20 psi

SOURCE: unloader valves

Yes, your compressor will work just fine with a Load Genie continuous run unloader from www.grainger.com. The part number is 4tk14 with a cost of about 45.00. This unloader has a built in check valve so you can remove the present in-tank checkvalve and save it for later use. All that you need to do is install the unloader at the tank and compressed air in to top of valve. (you may have to buy extra fittings to make it work with your tubing size) Adjust valve to open just before the pressure switch cut-off setting. The unloader will bypass the compressed air and will have less stress on the motor. You will not need to use the present unloader at the pressure switch. The only caution is to manually unload the Load Genie upon initial start if there is pressure in the line. Good Luck with your project.

SOURCE: The compressor starts and stops after a short

More than likely it is a problem with the inlet control, commonly I have found wear in the throttle linkage can cause this or a faulty sump pressure sensor that is out of calibration.

Joe Garcia

• 210 Answers
• Posted on Jun 15, 2011

SOURCE: I have a Craftsman compressor

you must have wired the new pressure switch incorrectly .when the pressure switch opens it will release the head pressure so your compressor must be running with the pressure switch contacts open should be 4 connections 2 marked motor which is from your compressor and 2 marked line which is your power coming in

SOURCE: I have a vt631401aj campbell

John: I had a similar problem with a brand new CH-made compressor. The problem was not with the unloader valve, but with the check valve located where the air from the pump enters the tank. The check valve was not seating correctly due to brass filings from manufacture. The defective check valve was allowing air to escape back the wrong way from the tank to the pressure switch and through the unloader valve. This backflow from the tank would start to happen when the pump stopped after reaching high pressure. The back flow would continue until the pump restarted at the low pressure point. This cycling would continue as you described. Once I cleaned the check valve, everything (including the unloader valve) started working correctly. I hope this helps. And remember, don't work on these when they are under pressure and always wear safety glasses.

SOURCE: I have central pneumatic 21 gal. air compressor.

If you should mean the switch that is pressure controlled that turn the compressor on and off- that is a fairly universal replacement piece, As is the power switch itself

If you needed that specific part, your best bet is Harbor Freight tools who owns the Central Pneumatic domain.