Central Pneumatic 67847 compressor only runs for a few seconds

by Tom
(Whitehall,Pa)

My compressor runs for a few seconds then cuts out ?

I put new pressure regulator switch on lf-10h same as the one that was on there still does same thing.

Have to keep hitting reset button to build up more pressure I have plugged into 20amp circuit with nothing else on that breaker.

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My first thought would have been the pressure switch too, Tom.

However, when you say “have to keep hitting reset button to build up more pressure” that is suggesting to me that the motor is overheating.

Good that you have the 67847 plugged into a 20 amp breaker.

Tell me as a comment, do you feel that the motor is overheating?

If so, time to check the run capacitor I think. See how to test a compressor capacitor here.

And, a 67847 Compressor keeps overloading reset switch

by lou

i have a central pneumatic air compressor #67847. i just brought it used.

when i went to turn it on, it would run for 20 secs then shut off , maybe building up to about 40 psi. i have to hit the reset button to kick it back up but it wont build pressure past that. it’ll just run for a few then shut off again.

then i checked the fluid levels an realized they filled it past the full mark, the oil was black which was a bad sign also.

turned it on again an it reached past 90 psi but it popped the reset a couple times during that process, and sometimes when i hit the reset it will hum then pop the reset again.

the pressure switch is broken also because it’ll stay on even though the lever is in the off position, what can be the problem

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Lou, probably a couple of things.

Check the unloader valve to make sure it’s working, and do that by seeing the the compressor starts OK with the tank totally empty.

While you may have a pump problem, I’d check the start capacitor next. See that page on this site.

Another 67847 trips & resets issue

by: Brian

Ok I have a 67847 about 3-5 yrs old.
compressor does not like low voltage…
Hence 50ft ext cords.-;) 12awg only.

Mine would stall on roll up if on long ext cord.( Low voltage)
Low voltage = high current more than 14 amps then the overload or thermal protector trips.

First empty all the air from the compressor.

Changed the oil by draining from the sight glass.
Add new oil only to the level just at the middle of sight glass.

Ran compressor with amp clamp meter reads 120v @11.82amps at zero psi.= unloaded

This is important to understand.

The Tank is the load for the compressor.
0psi = unloaded. 125psi= full loaded

The compressor is the load for the motor.

11.82amps=unloaded. 125psi= less than 14amps

A motor pulls whatever amount of current amps it needs to turn at full rpm.

Let’s say motor turns at 1750 rpm @60hz 120v.

Tank fills up so 11.82 amps increases but remains below 14amps until pressure switch cuts out at 125psi.

If you have low voltage you will exceed 14amps.
Then trips the protection overload.

If your pressure switch contacts are worn out
Due to on /off work cycle use that to will cause low voltage.

If the piston rings have damaged the walls of the cylinder this will increase load by friction since oil can not lubricate. It will trip the protection.

If you have always used your air compressor and it slow starts or trips of as you start with or without the ext cord. Then it’s perhaps time for a new capacitor.

A capacitor makes up for for low voltage upon the motor starting. However constant slow starts indicate low voltage.

Capacitors do have a limited operating life.

I hope this helps. But hey… for $179.00 it’s all fun huh? -;)