Do you have any evidence to suggest this compressor _should_ work on a 20
amp breaker? I think it's reasonable for the motor to draw twice as much
current under load as without load. How many horsepower does the motor say
it puts out, and how old is it? Multiply hp X 750 to get watts, divide that
by volts to get the approximate amperage, then fudge that up some since the
motor's not 100% efficient, and you have the current the motor probably
needs.
Chances are, if the compressor can build up 90psi, it's doing fine. I think
the most common failure mode is that the rings or valves stop sealing as
well (just like in an engine) and the motor keeps turning but you're not
building up more pressure. This is what I'd expect to have happen if it was
run dry for a long time. The other possibility is that when the compressor
piston(s) heats up, it siezes. If you let the compressor cool off for half
an hour or so after building up 90 psi, will the motor start and build more
pressure?
If the regulator is turning off the motor too soon, that can be
fixed/replaced pretty easily after making sure the tank, etc. are rated for
more pressure than the regulator is letting you build up. If you're blowing
the breaker before the regulator kicks in, the regulator's probably not your
problem.
keithka
'61 Elva 300 FJr.
> -----Original Message-----
> From: Brad Young [SMTP:byoung@ti.com]
> Sent: Monday, May 04, 1998 5:23 PM
> To: shop-talk@Autox.Team.Net
> Subject: air compressro
>
>
> Folks, I am getting a used air compressor. FREE. However as with
> most things there is a slight problem.
> It shorts out a 20amp breaker after pumping up to 85-90lbs,
> Things I know
> 1)The controller has been replaced.
> 2) The compressor was run low on oil at one time. a couple of years ago. I
> am not
> sure how long.
> 3) I need to determine wether it is the compressor or the motor. (or is
> there something else)
> 4) The motor draws around 12amps with no load. I understand that this is
> normal
>
>
> Does any know of how to diagnose this problem. Any ideas would be
> gratefully accepted.
>
> Thanks
> Brad Young
> 78 midget (mr goofy)
>
>
>
>
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