JOHN T....need help!

Bear with me while I try to describe my dilema , John. I've got an Ingersol Rand 5hp/220/80 gal tank industrial air compressor. Bought new in 1981. Baldor motor/magnetic starter.200 amp service to shop.PROBLEM: Has lost it's "start-up" power. Will just roll slooooowww and maybe once it gets going will run and start up fine the rest of the day. Usually trips breaker though. Unloader works fine. Will even do this when completely discharged.Like I said , once it starts up , it is good for the day,works perfect. Never has been a real good starter below 25 degrees. Usually let the shop warm up before starting. This problem , though , doesn't care what temp it is. Under the large cover on top of the motor there are 3 what I call capicitors? Two of them are aprox 4" long and 2"dia , 216-240 MFD...230 vac 60c #61302. The other one is same length only oval and metal,not plastic. It says 20MFD , 370 vac , last 3 digits are 301. There are 4 wires , 2 white and 2 yellow comming out of motor to these. What are these and what do they do? What baffles me is why it works perfectly fine after one start / stop cycle. If there is any more info you need to diagnose this let me know. As always , thanks in advance,John, for any advise. This is probably an easy one for you. Randy.

The start capacitors, the ones with the higher value are bad, or the centrifugal switch that connects them is sticking open. Happens a lot with dust around that the switch sticks.

Gerald J.

Thanks , Gerald , being in the area of body/paint dust will check and clean before going any further. That would explain why it works fine after run time but not first start of the day. Will post results tomorrow.

You'll probably have to take the end bell of the motor off opposite the shaft. Mark it with a scribe mark to make aligning it easier. And if you strike the core of the motor inward, the end bell will often pop off after you take the screws out. Hit it several places.

Gerald J.

Had to start my fall bush hoggin yesterday and check on my buddys bus then we went square dancing, just now back here on Sunday AM

Glad my friend Gerald J helped ya, he's more knowledgeable on that AC motor stuff then I am anyway, Im a too long retired EE but I think that rascal is still practicing it.........

Yep the start capacitors give much extra starting torque because they sort of electrically fool the rotor by yielding more opposing magnetic field offset to get it initially turning (something like that) They also use capacitor start and capacitor run motors (may be what you have???) so since starting not running is your problem I agree with what Gerald is thinkin.

Also at rest the centrifugal start switch is closed which places the start winding INCLUDING ITS SERIES START UP CAPACITORS) in the circuit but its supposed to open at x RPM,,,,,,,If it has a problem and isnt closing back full when the motor is shut down THAT MAKES GERALDS DIAGNOSIS sound good to me

The only thing I might add is Ive seen those push on terminals on those capacitors get worn and/or corroded or loose causing poor resistive or no contact so you may wanna first remove n clean n tighten them all down,,,,,,,,maybe see if you can use air to blow out some dust in the switch area then afetr all that giver her a try???

John T

Thanks for your help , John and Gerald , will get at it again this afternoon (after get done with wifes errands)and let you know what I find. Seems the capicitors would do it EVERY time if they were bad so hope that's not the case. Will keep ya updated. Thanks again. Randy.