Sanborn Black Max Air Compressor Slowing Down

11 years 3 months ago #117 by Ozarkwalker
Sanborn Black Max Air Compressor Slowing Down was created by Ozarkwalker
I have a Sanborn Black Max air compressor. 120 volt 5 hp motor. It has worked fine until yesterday when I started it. It started up fine, but the motor started slowing down as air pressure was building up. My thought is that the capacitors on the motor have gone bad. Any ideas. The oil in the compressor is fine. That is the first thing I checked other than that am I looking at a new motor or something a lot cheaper?

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11 years 3 months ago #118 by MTR-Admin
Replied by MTR-Admin on topic Sanborn Black Max Air Compressor Slowing Down
Thank you for the inquiry.

Most likely the problem lies with the motor or capacitors. I would have the motor tested as well as both the run and start caps (although the Run Cap is more likely based on the symptom).
I've attached a tech doc on how to test the capacitors (unless you have a capacitor tester handy).

Next, make sure the Belt Tension is not too loose or tight and the pulleys are aligned. You want typically a 1/2" of deflection in the Belt.

Make sure there is no obstructions in the Discharge Tube and in the Pump Head. I've included a tech doc on trouble shooting compressors, hopefully this gives you some assistance.

And please feel free to share the solution here once you find it!
- MTR
Attachments:

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11 years 3 months ago #119 by MTR-Admin
Replied by MTR-Admin on topic Sanborn Black Max Air Compressor Slowing Down
I should also say, make sure you don't run the unit on an extension cord, this many times can cause this problem.
Thanks!
- MTR

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11 years 3 months ago #120 by Ozarkwalker
Replied by Ozarkwalker on topic Sanborn Black Max Air Compressor Slowing Down
The ohmmeter only goes up to R*10. According to it both capacitors are open.

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11 years 3 months ago #121 by Ozarkwalker
Replied by Ozarkwalker on topic Sanborn Black Max Air Compressor Slowing Down
It was one of the capacitors. A local electric motor repair shop has the one I needed in stock.

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11 years 3 months ago #122 by MTR-Admin
Replied by MTR-Admin on topic Sanborn Black Max Air Compressor Slowing Down
Great to hear you narrowed the problem down! This is a pretty typical problem.
Thanks for posting!
- MTR

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