Recently, I harvested a fist-size electric motor from an old portable space-cooler (an air-conditioner on wheels). The motor has nothing written on it at all; brand nor specs. It has 5 (five) coloured (grey, black, yellow, red & blue) wires. I'd love to power it up and use it for some project - a mini-wood turning lathe for example. With absolutely no information on the unit, is there a safe way to test the motor based purely on the color-coded input cables?


I would try to get the technical information for the equipment it was salvaged from (start with Google). If you find that, it should tell you everything you need to know.

I would not assume that the color coding taken in isolation means anything. Lacking the service info, I would look at what I knew about the original equipment - was it run from household AC? Was the motor for a variable speed fan? A refrigeration compressor? Or...? Then I would try to determine type of motor it appeared to be: split phase? capacitor start, run or...? Next, get out the ohmmeter and trace out the connections. How many actual separate windings are there? Are some tapped?

Assuming this is from consumer grade equipment, it "sounds like" a fan motor with several run windings, each for a different speed, but that's very much a W.A.G., and doesn't tell you how to connect it. However, judging only from the size, it is probably far too low powered for a lathe.

  • \$\begingroup\$ Thanks mickeyf. The motor was for a variable speed fan not a compressor. I may just use it as a doorstop. Without information on the original unit it may be a lost cause. \$\endgroup\$ – Ramlee Oak Nov 22 '12 at 6:58
  • \$\begingroup\$ @Ramlee On the other hand, with experimental connections you have nothing to lose but the magic smoke. And it will still make just as good a doorstop after that! If an ohmmeter indicates that it has a single winding with multiple taps, you might try connecting (briefly, and with a fused supply) to the highest resistance ends, then moving one side of the power stepwise from one end to each lesser resistent tap point in turn. \$\endgroup\$ – UnconditionallyReinstateMonica Nov 24 '12 at 3:34

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