air compressor keeps blowing breaker

[robzilla]

need some help to trouble shoot my compressor. it's an old unit, and when it tries to cycle, it blows the breaker. if you give the pulley a little help, doing start up it will cycle just fine.
where do i start to trouble shoot?

[robzilla]

took the belt off, and the motor runs fine, but with a load it struggles then blows the breaker. it's a gould 1 hp motor, are these rebuildable?

[mbgmike]

I would just buy a new motor. A 1 hp is not expensive. From my experience the small motors are not worth the cost to rebuild unless thats the only option. I buy and sell used industrial compressors on the side. After trying to find pro companies to rebuild motors the cheapest way was just to go buy them cause I re-sell them. Check the amp draw on the motor and see if the breaker is correct. ALso you have little tiny wires wrapped in with the main wiring on the armature. They pull the armature so it will know which way to turn. If the they weren't their the armature stays where it is and hums. These may be failing. I went years like that starting a grinder just pulling it to get it started. Check the capacitor thats what kicks these wires in gear. If bad it can draw double the amps which will trip the breaker. If on and old motor that may be the only thing youy can replace besides the cord

[cdowns]

i'd change the oil in the compressor pump// i prefer synthetic

[mbgmike]

did it ever work fine where you hook it up now?

[mbgmike]

Originally Posted by cdowns

i'd change the oil in the compressor pump// i prefer synthetic

thats the cheapest to do first. i agree

[stich626]

what is the wire running to it 10/3
does it do this every time or only after it's fulled the tank and try'n to refill?
what breaker you use'n.. my compressor draws 30 amps

[robzilla]

Originally Posted by mbgmike

did it ever work fine where you hook it up now?

yes it worked fine before. my brother in law passed it over to me when he started to have problems with it.

[robzilla]

Originally Posted by stich626

what is the wire running to it 10/3
does it do this every time or only after it's fulled the tank and try'n to refill?
what breaker you use'n.. my compressor draws 30 amps

yes, it does it every time it goes to start up to refill the tank, without the belt on, it runs fine but once it has a load it blows. i need to check the wire guage, but it used to run fine before

[mbgmike]

If our wire is good, comp is on a dedicated or at least a circuit with a 15 amp breaker it should be fine for a 1 hp or less. Thats probably what you have with a 1 hp. Unless you see lights dimming etc. if thats ok and it sounds like it may be. you only really have a few more options

the capacitor is bad

or the unloader valve/valves. When the compressor trys to start with pressure in the tank, you should hear a short burst of air. Thats the unloader letting of some of the pressure off to help it turn over. some compressors blow the air after its up to max. If thats stuck or bad it can cause the comp to not turn over and blow the circuit. kind of like pop off valves on a high compression motor.

I would check them after making sure the wiring is ok

[Sub-versive]

Originally Posted by mbgmike

If our wire is good, comp is on a dedicated or at least a circuit with a 15 amp breaker it should be fine for a 1 hp or less. Thats probably what you have with a 1 hp. Unless you see lights dimming etc. if thats ok and it sounds like it may be. you only really have a few more options

the capacitor is bad

or the unloader valve/valves. When the compressor trys to start with pressure in the tank, you should hear a short burst of air. Thats the unloader letting of some of the pressure off to help it turn over. some compressors blow the air after its up to max. If thats stuck or bad it can cause the comp to not turn over and blow the circuit. kind of like pop off valves on a high compression motor.

I would check them after making sure the wiring is ok

Spot on.

[robzilla]

took off the cover housing the wiring and this is what i found:





i cleaned up the wiring but it still blows the breaker. i opened up the pressure release valve, it seems fine. now it seems to leak once the compressor cycles and shuts down once it filled up.

where is the capacitor? how do i check it?

thanks

[mbgmike]

I could say how but

YouTube - Hvac motor start capacitor check

[72lb4x4]

The start cap is probably under the rounded cover on the top of the motor. You can see it in the pic above.

[robzilla]

looks like i'm looking for a new compressor...it will start 3 out of 5 times....seems like there is resistance within the pistons or shaft. if you try to turn the wheel, it feels like its stuck but once you break it free, it starts to run.

[Torrey72]

Originally Posted by robzilla

looks like i'm looking for a new compressor...it will start 3 out of 5 times....seems like there is resistance within the pistons or shaft. if you try to turn the wheel, it feels like its stuck but once you break it free, it starts to run.

Don't be shy! Tear that bad boy apart. and fix it.
I got an old used up Snap-on compressor years ago. I striped it down, cleaned it up, cleaned the points on the switch, flipped the bent read valves over and reassembled it with gaskets I cut out from a cereal box. I replaced the motor with one from Harbor freight as well. It still runs perfect to this day. That little project saved me $800 or so I bet. I still see hope for yours.

[buffle]

My 10 horse 120 gal compressor used to do this occasionally. A local electrician had me buy a slow blow breaker and it solved the problem. I guess it handles the initial surge on startup