Air Compressor to 110V - Devilbiss Pro Air


Old 08-21-17, 04:51 PM
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Air Compressor to 110V - Devilbiss Pro Air

Name:  Compressor Motor Label.jpg
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Size:  19.8 KBI have an air compressor. I think it was from Sears perhaps 20 years ago. It's a Devilbiss Pro Air 5 HP, 20 Gal. The motor is a GE Mod 5KCR49SN2137X which also says MO-9045. It can run on 115 or 230 (according to the label). Of course you need to change some wires around but there's a clear placard showing the steps. Also, on this web side, searching on the Mod number (above) there is a very good post on how to re-wire. Basically, just move the Brown (P2) and White (T2) wires.

It works fine on 230 and has for quite some time but I'd like to rewire for 115V. I made the change, as described. Checked and double checked. Changed the plug. The whole works. The motor barely runs. It may turn over a few times but it's sluggish. It seems like it's running on 115 but is expecting 230... IE it acts dramatically under powered.

This would suggest that there's something more than just the Brown and White wires.

Does anyone have a wiring diagram of this motor? Perhaps a picture of it configured for 115V? Any suggestions on how to make it work on 115V? I attached a picture of the label.

Thank you for any help.
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Old 08-22-17, 03:36 AM
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Thumbs up Welcome to our forums!

You need to understand that if you change the wiring to 115 volts the start and running amperage will double.
I can't quite see the tag but the higher amperage number would be @115 volts.

it is possible that it is wired correctly but the circuit can't handle the current.
Old 08-22-17, 06:38 AM
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Name:  Motor Wiring.jpg
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Size:  78.7 KBNo, it's on a 20A circuit and the breaker didn't trip. The motor is rated to draw 15A at 115V and 7.5A at 230V. That's one of the reasons I switched over to 230V.

Sadly, I seem to remember another wire that had to be changed, which wasn't documented. I thought I'd written it down but can't find it after all those years.

I attached a picture. The label only shows 4 wires (because those are all that are relevant). The two input lines, black and white, pretty much centered in the picture, and then the brown and white movable wires (different white).

There are a total of eight wires:
Black, In
White - In
Another black lower down - ?
Orange, far left - ?
Brown - Movable for 115 to 230V
White, movable for 115V to 230V (seems to be on a common lug with the Black AC In)
Yellow - ? (seems to be on the common lug with Black AC)
Purple - ? - (above White AC In but no obvious connection)

Thanks for the suggestion... Any other thoughts from anyone? Anyone have a similar unit that could maybe take a picture?
Old 07-05-18, 07:26 PM
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Did you get it working?

Here is mine, still factory wired for 110V

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Name:  IMAG0186.jpg
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Last edited by PJmax; 07-05-18 at 08:49 PM. Reason: added two pics from links
Old 07-05-18, 08:53 PM
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Welcome to the forums and thanks for the pictures L33.

I'm not understanding why you want to convert from 240v back to 120v.
That's like taking a step backwards. The motor will run more efficiently on 240v.
Old 07-06-18, 02:36 AM
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I have a Sears air compressor I bought about 35 yrs ago - it was made by DeVilbliss.
I assume he wants to convert it back to 120 for portability.
Old 07-06-18, 11:00 AM
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In theory it is possible for efficiency gains in operating at a higher voltage.
In practical terms the problem is with too big of a voltage drop due to inadequate wiring.

It is a problem I have with my saw on 120 volts that is a fair distance from the service.
Just for fun I'll sometime measure the voltage at the saw while ripping a spruce 2x.
I'll post to this thread when I do so.
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