# motor continues to spin after compressor pump shuts off correctly.



## ervie (5 mo ago)

i have a vintage 1974 KARGARD portable (wheels) (also POSSIBLY known as a montgomery ward brand) its a single stage 1 hp.w/ quite a small tank prob about a 12-15 gallon tank. ive been working on fixing little things here and there finially ran it through a full cycle up to 120 psi. the compressor pump shuts off ok at 120psi but the motor shaft keeps spinning /motor is not running though. Is this a cool down feature or something? im just afraid that if i let it go too long spinning it might damage my motor.so i flip the on/off switch off. These old antique compressors dont seem to have check valves in the tanks or a pressure switch recognizable anywhere on my model. i just plug it in and flip a switch installed right off the motor mounted next to it.I've never experianced anything like this before with a compressor so im scratching my head looking for help. FYI i know the pic isnt a kargard but a reasonably close pic of my compressor. ￼i will try and upload a couple pics later if needed., thank you all in advance,


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## ervie (5 mo ago)

I forgot to mention also that while the motor shaft continues to spin this OfCourse also keeps spinning the compressor pump wheel too which makes me think it's acting as a cooling fan effect mechanism somehow for the pump after it shuts off. But again, i have never seen anything like this happen before.


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## ervie (5 mo ago)

these are all similar model set ups to mine


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## motormonkey (Jul 10, 2016)

"... the compressor pump shuts off ok at 120psi but the motor shaft keeps spinning /motor is not running though ..."

How can the compressor pump shut off and the motor shaft keep spinning???
How can the motor shaft keep spinning if it is not running???


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## ervie (5 mo ago)

yep! thats my big question!


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## tabora (Sep 6, 2018)

ervie said:


> yep! thats my big question!


I think you'll have to post a video of this happening so we can understand exactly what you're seeing...


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## iowagold (Jan 22, 2020)

check the one way valve from the compressor to the tank.

then check the pressure switch it maybe welded stuck to on


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## stevon (Mar 5, 2019)

ervie,

Does this compressor have an "idler" pilot valve? They are used with gas engines to let the motor run without compressing air. Also used for constant run to keep motor and cylinders cool for 100% duty operation.










Stephen


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## MacMcMacmac (9 mo ago)

I think Paul is right, the switch is tripping and the blowdown is actuating, but the contacts are still closed.


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## stevon (Mar 5, 2019)

motormonkey,

So you are saying the compressor keeps pumping after the pressure switch turns off? and the overpressure safety release is venting? something has to give out thermal overload, safety valve venting, pilot valve releasing (if 1 exists), fuse blowing or a catastrophic tank rupture in the worst case, your question needs some clarification

Stephen



motormonkey said:


> "... the compressor pump shuts off ok at 120psi but the motormonkey, ..."
> 
> How can the compressor pump shut off and the motor shaft keep spinning???
> How can the motor shaft keep spinning if it is not running???


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## motormonkey (Jul 10, 2016)

I am merely quoting the original post with all its contradictions. The original post needs the clarification.


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## stevon (Mar 5, 2019)

motormonkey,

oops I ment to send my question to ervie, my bad

Stephen



motormonkey said:


> I am merely quoting the original post with all its contradictions. The original post needs the clarification.


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