Everytime I turn on the switch my compressor pops the breaker

Every time I turn on the compressor it pops the circuit breaker been in the same place for 7 years. not sure if it is the motor or pressure switch how to check?

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Bill answers...

Howdy:

That's a tough one to answer without seeing the compressor and watching what happens and since you don't indicate if the power interrupts instantly, or after a time period (what time period?) has passed.

I take it it's been in the same location for that 7 years and you've only recently seen this problem?

Next question. The last time you used the compressor when it was running, when it reached cut out pressure, did the compressor unload? If it didn't, air trapped over the piston could be increasing the load on the motor to the point where the amperage pull exceeds the capacity of the circuit and pops the breaker.

Assuming you haven't got a short in the supply cord to the compressor (which sounds unlikely since it's been in the same place for that long), and that the compressor unloads when it reaches cut out pressure, then I expect you are right. It will be a problem with pressure switch or the motor.

Do you have some electrical background? If you do, then you'll know how to use a multimeter, and be able to check current draws and resistances, etc. My multimeter use is limited to checking the voltage of a circuit, so it were me, that advice wouldn't help me much! :-)

When you say it pops the circuit as soon as you turn it on, I understand that to mean that you've got an on/off switch, or a toggle switch of some kind on the pressure switch, and it's the flipping of that to the run position that pops the breaker?


If the breaker doesn't pop instantly when you turn it on, I'd remove the cover from the pressure switch, and watch as you (very carefully not to touch anything electrically live) flip it to the run/on position. What happens? Do you see an electricity arc as the breaker pops? Any movement of any of the switches internals?

If the breaker pops instantly, then I'm going to suggest that it's the pressure switch that's causing the problem (and that's the least expensive of the problem options) and I'd change that out first.

If it were a motor problem, unless you've got a short in the motor or starter, it may be that the motor is trying to start, and since it can't start, the motor amperage draw exceeds the capacity of the breaker. And that would take some time to happen unless it were a short.

If you need a pressure switch, here is one that should work. The photo is a link.






You may have to finagle with the line from the compressor head to fit into the fitting under the switch, shown on the left in the photo. That's the unloader valve, and it must work in order for the compressor to start.

If changing out the pressure switch doesn't work, you do two things. Put the new switch onto your shelf to use next time you have a pressure switch problem, and then you take your compressor to the shop and have them check it out. Or, you remove the motor and take that to a motor shop and ask them to diagnose if it is causing the problem.

Cheers,

Bill