Jun-air compressor motor will not turn.

by Greg
(Naples, Florida, USA)

Jun-air compressor

Jun-air compressor

Hi,


I have a very old Jun-Air compressor that I used to use for airbrushing. Fired it up the other day and the power cut off immediately.

Pulled the top off and looked at the unit. The central spindle seems very hard to turn. I suspect it is either seized up or that the pump is having a hard time pulling in air if that makes sense. It gets progressively difficult to turn, then seems to equalize pressure or something and then gets easy again for about a half rotation, then gets really hard to turn.

Unit has plenty of fresh oil.

I suspect that the drive is too difficult for the motor to turn it and that is what is causing the power supply to trip off.

Any suggestions would be helpful.

Thanks,

I have uploaded a stock photo of the model I have.

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Apr 16, 2018
Buy new?
by: Bill

Yup, they are expensive, and yup, they have more competitively priced competitors now, though I don't see many (or any) with the very low noise level of the Jun Air brand.

The rebuild cost will be a fraction of a new one, whatever brand.

Whether you invest in a a rebuild will depend, I think, on how the compressor was used... or abused! Old doesn't mean unreliable, particularly if it has been well maintained and / or the use level has been fairly low.

Good luck.

Apr 15, 2018
Thanks for the reply about Jun Air compressor
by: Greg

Will check the valve. In your opinion would it be worth it to repair the unit? It was expensive when I bought it, but it has to be at least 10-15 years old and has held up well. Just wondering if it is prone to have multiple problems developing at this point.

Apr 15, 2018
Jun-air compressor motor
by: Bill

That it starts suggests that it isn't a motor issue.

I suspect a pump problem, likely a valve seized. Or, it might be a bent crank or a piston issue. Either will require a pump tear down.

First though, you might also pull the tank check valve and ensure that it isn't blocked.

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