Compressor humming for a few seconds, then tripping breaker - SOLVED!

[ebscreen]

are you in FL? We had the same thing yesterday. It turns out that one of the legs was blown at the pole. We had power for the lights, dryer... Everything seemed fine so I thought my compressor motor froze. I hooked the spare up and had the same problem. The FPL guys got it fixed in 3 minutes. They said anything with a big motor was effected. Everything else was fine.
Good Luck.

This happened to us as well, third leg of three phase got bit by a squirrel at the box and was intermittent.
The PG&E (our power co.) dude tried to get out of fixing it. Literally.

FWIW our meters have indicators for each leg, a little flashing/solid A/B/C. Easy check.

[sqslabs]

are you in FL? We had the same thing yesterday. It turns out that one of the legs was blown at the pole. We had power for the lights, dryer... Everything seemed fine so I thought my compressor motor froze. I hooked the spare up and had the same problem. The FPL guys got it fixed in 3 minutes. They said anything with a big motor was effected. Everything else was fine.
Good Luck.

Yes, South Florida.  Thanks for the heads up, will look into it.  My dryer has been setting off some weird alarms the past couple days as well, was going to run through the sensors this weekend but maybe they are somehow related.

I've attached a picture of what the compressor has two of in the side cover, are these start capacitors or run capacitors?  And if so is there a way to tell if they are shot (short of replacing them)?

[sqslabs]

and here's a pic of what is in the other compartment..

[sqslabs]

Gonna pick up a pair of these, hopefully it does the trick..

https://www.grainger.com/product/DAYTON-Round-Motor-Start-Capacitor-2MDU9

[balloonguy]

Be really careful with those. I was told by a compressor tech that they can hold a huge charge for days or even weeks.
If you need compressor company I love the guys I use. They are in boynton but I am sure they service broward too. AirCoMo is the company. Let me know if you want the contact info.

[sqslabs]

Be really careful with those. I was told by a compressor tech that they can hold a huge charge for days or even weeks.
If you need compressor company I love the guys I use. They are in boynton but I am sure they service broward too. AirCoMo is the company. Let me know if you want the contact info.

Thanks for the heads up, I just wish I would have seen it before I pulled them ha!  I shorted them with a screwdriver per Binkspot's recommendation which seemed to work as I am still alive. 

In other news, I just replaced those two capacitors with a pair I got at Grainger and it fired right up on the first try!!  Can't thank everyone enough for the help today, it is really appreciated.  This definitely isn't my area of expertise, and I was nervous the compressor was a goner.  I wouldn't have been able to get a tech in here until tomorrow and it's a lot nicer to head home for the weekend knowing that the press will be spinning on Monday.

You guys, and this forum, are the sh1t! 

[mk162]

capacitors tend to go out when it gets hot.  It's about the best place to start.

your AC sytem has them too and a $15 capacitor will cost around $250 from a service company to come fix. 

[Binkspot]

Get a spare set of start and run to keep on hand.
Used to charge and toss them to an unsuspecting person, always good for a quick laugh.

[mk162]

i friend of mine would charge them and leave them sit around the shop and office just to mess with folks

[sqslabs]

Alright, so everything was working fine yesterday and a few minutes ago the compressor kicked in, made some weird noises, threw some blue sparks around inside the motor and then tripped the breaker again.  I replaced the start capacitors the other day, and will now replace the run capacitor, but is it possible that something is wrong with the motor otherwise that could have caused the capacitors to go in the first place?

Anyone selling a compressor?  I'm due for an upgrade.   

[Binkspot]

The governor in the back of the motor may have a broken spring. Get a new motor or compressor. Go rent one to get you through if needed

[sqslabs]

The governor in the back of the motor may have a broken spring. Get a new motor or compressor. Go rent one to get you through if needed

Thanks for the response.. I've made the decision to upgrade to a rotary screw in the next few weeks, and hope that I may have solved the issue to get me through until then. 

The run capacitor is housed in a compartment on top of the motor, and is held to the top of the housing by double sided tape.  I pulled everything the other day and replaced the tape when I put it all back, but when I opened the compartment back up, the capacitor had fallen off the tape and was sitting on top of the motor.  I put a 2" piece of foam under the capacitor and replaced the housing, and it seems to be running fine again. 

Is it possible that the capacitor sitting on top of a running motor could have caused the symptoms I saw today?

[Binkspot]

The terminals could have been dancing around grounding out.

[sqslabs]

The terminals could have been dancing around grounding out.

Thanks, that would definitely make sense.  Still running well this morning so fingers crossed that was the issue and we'll hold up until I get a new unit in here.

[blue moon]

we are shopping for a screw compressor right now too. Atlas has a special of some sort that seems to be about 25% off the regular price. . . Do you need a contact to call?
we are looking at 7.5HP with built in chiller, dryer, carbon filtration unit and auto drain for about $7K.

pierre

EDIT: scratch that, it does not really seem to be that much cheaper. They are advertising the GX5 with chiller and dryer built in at $6,167, so that's about $600 below internet pricing.