Start relay (capacitor) or pressure switch?

Jun Air 6-25 (12 yrs old) started having problems starting after dropping air pressure with normal use.

Just had unit serviced/repaired at a Jun Air dealer. A braided hose+non return valve and regulator were replaced.

I was told the unit was tested and ready to pick up after 2 months at the dealer. I plugged it in, put switch on "auto" . Motor started and filled tank to 120 lbs then shut off.

As I used air to below 60lbs , I can hear motor trying to start (green light on then off) but motor never runs. This will continue for up to an hour when the unit will finally run and cycle up to 120lbs.

Dealer told me pressure switch may need to be adjusted. I have tried that, adjusting "cut in" and "cut out" settings and still have same problem. Pressure switch seems to be functioning properly from what I can tell.

Do you think I may have a start relay or start capacitor issue?

Alpo Nyberg Dental Lab

Comments for Start relay (capacitor) or pressure switch?

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Jul 16, 2015
Jun Air Start relay (capacitor)
by: Bill

If your unloader valve is working, then yes, it is quite possible that the start cap is the problem.

Empty the tank, make sure it's on a dedicated power supply, and if it starts, monitor the unloader valve to be sure it operates.

If the unloader valve works on cut out, then if this were my Jun Air I'd be checking the start capacitor next.


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