Question about Craftsman 3 gal. Air Compressor, 1.5 hp, Horizontal k

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Craftsman aircompressor bogging down

Motor running at half power I have a Craftsman Air Compressor, #921.153101 when it starts running it will get to about 40lbs of pressure and then will act as if it is bogging down and the motor really starts pulling. I had the capacitors checked and also took the motor to a rewind place and they all checked out fine, until you put it under load. I was wondering if it might be the check valve or pressure switch,or if its in the compressor part. any help is greatly appreciated

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Yes , the check valve will cause this. The check valve has a flat disk with a spring that holds it down that the air passing past it erodes away till it leaks then the air that the piston pushes into the tank does not stay in the tank but returns right back into the cylinder and puts a load on the piston. Also makes the compressor hard to start back up if it does get pumped up. Some have a dump valve that drains the pressure off the head after they shut off so it can start with no load. So if there is air bleading back and leaking at the pressure swith that will be a for sure sign it is the check valve.

Posted on May 20, 2009


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