# Ridgid compressor trips breaker



## Forrester (Aug 11, 2021)

Have a Ridgid of50150ts that does the classic "starts fine on empty tank but fails and trips breaker when there's any air in it".

I have already replaced the check valve and the start capacitor. Haven't replaced the pressure relief/unloader valve because I'm pretty sure I can hear the air escape from it when the motor shuts off.

Should I just give in and replace the unloader valve, or is there a way to test it first or something else I should look at? I don't have much experience with compressors and don't want to keep throwing parts at it unless I know it's going to work.

Any help appreciated, thanks!


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## iowagold (Jan 22, 2020)

replace the unloader and the check valve


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## Forrester (Aug 11, 2021)

Ok, I have already replaced the check valve so I'll try the unloader next, thanks!


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## iowagold (Jan 22, 2020)

yea if it is dead heading the tank pressure and not free wheeling till it gets up to speed it will do that...
also check the start switch if it has one to make sure it is working right.


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## Forrester (Aug 11, 2021)

Got the unloader valve in today and replaced it, still does the exact same thing. So I've replaced the check valve, unloader valve, and start capacitor now. 
Problem still the same. Will not restart unless I empty the tank. Motor makes a humming sound and tries to start, but fails and trips the breaker. On empty tank starts perfectly fine every time.
Start switch has continuity when it should. 

Any other ideas what this could be?


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## iowagold (Jan 22, 2020)

is there two caps?
check the start switch


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## Forrester (Aug 11, 2021)

Like I said above the start switch has continuity when it should, other than that I'm not sure what you want me to check on it? It has continuity when turned on and breaks the connection when turned off.

Yes there's two capacitors, I haven't tested the run capacitor because I can't figure out how to get my multimeter to test it. I just replaced the start one.


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## iowagold (Jan 22, 2020)

do you have a cap test setting on the meter?


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## stevon (Mar 5, 2019)

Sounds like the starter switch or "clutch" has an open circuit. It should be closed and conduct (short) at 0 rpm thus putting the start capacitor inline with the windings. The windings in the motor might have a problem. How many amps are drawn when tank is empty? How many amps when air pressure exists in the tank?

Stephen


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## Forrester (Aug 11, 2021)

Hmmm... Yeah I have little experience measuring current and not even sure how I would do that. But if it's something in the motor I think it's time for me to chuck this thing in the trash, I was hoping it would be an easier fix but I guess not.

Thanks for the help anyway guys!


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## stevon (Mar 5, 2019)

Forrester,
Checking current is easy with a cheap ammeter like one from Harbor freight:









6 Function Mini Clamp Meter


Amazing deals on this 6 Function Mini Digital Multimeter at Harbor Freight. Quality tools & low prices.




www.harborfreight.com












You use it on only one of the "hot" conductors (not a ground wire):









An Ammeter is a useful tool and worth the $14 even for a cheap one.

Stephen


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## stevon (Mar 5, 2019)

Forrester, 
When an electric motor is started under load it draws "LRA" or "locked rotor amps" for a second or two then current should drop down just below FLA or "full load amps". this is listed on the motor









It seems that you are drawing more than FLA , do you see or smell burned wires? Let us know how many amps are drawn under load and what the FLA is listed on the motor. Other than a bad bearing or other extra load it looks like you eliminated the usual check and/or unloader valve possible problems. can the motor be replaced?

Stephen


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## Forrester (Aug 11, 2021)

Well that tool would make it easier! I didn't know about those, maybe I can pick one up. Not sure if the motor can be replaced, or whether it would even be worth it if it could, it's one of these little units:


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## Forrester (Aug 11, 2021)

Oh one thing that is a bit strange...

When it trips the breaker, it doesn't trip it's own breaker (which it has), it trips the house one to the outlet it's plugged into. I would think the whole point of having a reset switch on the unit is that it would trip that breaker, but it doesn't.


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## stevon (Mar 5, 2019)

Forrester,

Looks like a 120 volt compressor. On the supply circuit, I would check and/or tighten the lugs on the outlet or replace the outlet, also tighten on the circuit breaker side (be careful, pull out the breaker, tighten screw than snap it back in). Circuit breakers do wear out eventually. Also is the outlet used or "daisy chained" to other outlets and other loads share the circuit at the same time?
is the plug unusually hot when compressor is running? An ammeter would really help diagnose the problem and probably save money too in the long run. That is where I would start myself, just saying....










Stephen


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## stevon (Mar 5, 2019)

Forrester, 

Warning! disconnect power before any tightening of terminals. If you are not confortable/knowlegeable about electrical circuits *get a qualified person* to help you!


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## stevon (Mar 5, 2019)

Forrester, 

I looked into the Ridgid of50150ts and it is one of those "disposable" oiless compressors. Meaning that it is manufactured so cheaply, that it usually cost more to fix than to replace the whole compressor, usually the cylinder/piston go first and sometimes the motors burn up. They can always be fixed/retrofitted but why? cost more to do that than buy another new compressor. I'm cheap and like to tinker so I understand the time taken so far. Make sure the outlet you plug this into is in good order and good luck!

Stephen


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