newbie needs advice re: electric motor wiring

[mibracedude]

I salvaged an old oxygen concentrator to get the small compressor out of it. The pump is a devilbiss ZW370D14 and can be used as an compressor or vacuum pump. I'm not only a newbie, but I am electronically challanged. My pump has four wires going to it out of a wire harness. I have no idea what happens to the current from the 120v going into the compressor before it connects to the 4 wire harness leading to the motor. I checked for current while the coconcentrator was running and found one 120v energized wire and one neutral, the other two showed no current. When I disconnected the harness and connected a live + and - to the same live wires I had identified, the compressor does not come on. I found a pictue of my exact motor for sale on another website with a mystery capacitor or coil leading from the 120v line tothe motor. Can anyone tell me what the mystery gizmo is so that I can get my compressor working. Can you please dumb down your advice for a newbie non electrician.

vacuum pump.jpg (14.35 KiB) Viewed 7867 times

[pebe]

The missing 'gizmo' is a start/run capacitor. In this type of motor the capacitor is used to get a phase shift in one of the windings. The relative phases of current in the two windings give a rotating field effect which makes the motor turn. A typical value would be from 1µF to 10µF rated at ac mains voltage.

I have Googled for details of your motor without success, so I suggest you contact Devilbiss who can then tell you the capacity and voltage rating of the capacitor required.

[mibracedude]

Thanks Pebe, very helpful. I have it running as a stand alone vacuum pump now.