Very Old Compressor

[Michael O'Sullivan]

I picked up an old (tank says 1973 ) Sears compressor on Craigs List for $50 yesterday. When I plugged it in, I saw found that it kicked out at 90 psi, even though it should go up to 150 psi. Then I realized that it wasn't kicking out, it had tripped the 20A breaker.

It has a 1.5 HP Westinghouse motor that, when I examined the info plate, draws 22 amps at 110 volts. Hence my problem.

I have 220 volt availability, but have never rewired anything. In looking at the wiring, there are 3 wires coming in, two attached to "line" and one to the ground, and there are 2 attached to "motor" that go out, unsurprisingly, to the motor. The lighter wires are on the left, and the darker ones are on the right (there are no colors anymore beyond light and dark).

Anyone want to fill me in on what I need to do? All advice is welcome.

[Jim Becker]

First things first...does the info plate indicate that the motor can run on 240v power?

[Jim DeLaney]

Take the wiring connection cover off the motor. Often, there's a diagram on the underside of it that shows the proper connections for 120 & 240 - assuming your motor is capable of being run on 240.

[Michael O'Sullivan]

Jim and Jim-

The motor says 115v/230v and indicates that it would draw 11 amps at 230.

There is no wiring diagram as far as I can see.

[Rob Will]

Why don't you drop the motor by a local electric motor shop and let them take a look? This might also be a good opportunity to freshen up the bearings.

Rob

[Al Killian]

Replace the motor with a for efficent one.

[Rod Sheridan]

Michael, I wouldn't run a 30 year old hobby grade compressor at all. You have no idea whether the previous owner drained the condensate from the tank.

You may have a garage destroying explosion just waiting to happen. If you're lucky, no one will be killed.

There are good reasons for requiring commercial pressure vessel inspections on a routine basis. Do yourself a favour, destroy the pressure vessel and purchase a safe, new one.

Regards, Rod.

[Ryan Myers]

How many wires are actually coming out of the motor housing into the j-box on the motor?

Also, does the motor have a thermal reset button?

You can use a continuity meter to read out the windings and rewire to the desired voltage very easily without the diagram.

If your not comfortable with this either get a knowledgable electrician to do it or take motor to a motor shop as a previous poster mentioned. Or feel free to PM me if you want me to walk you through the process.

I too would be a little leary of the tank. I have heard several stories of them exploding.

[Don Henthorn Smithville, TX]

But a recent discussion on the OWWM site pretty much debunked the idea that you risk a dangerous explosion from an old tank. The usual sign of failure according to the people who service these is a pin hole leak with rusty water coming out. None of them had ever heard of big bang coming from an old tank. Not that it isn't possible given the right circumstances, it is just that it is rarely, if ever, heard of. The concensous was that buying an old compressor and putting on a new tank would net you a better compressor than the ones sold today. I'm just reporting what I read. I am no expert.

[Jim Heffner]

Michael, you said it was not kicking out (reaching it's pressure limit setting), sounds as if you might have a defective pressure setting control
on the compressor. Check it out before attempting to change or re-wire
the motor and controls, sounds like this could be your problem. Jim