Old Compressor wouldn't turn on anymore, bought new one similar issue

by Chris
(Wilmington, DE)

Hi Bill, I have a Kobalt (Lowe's Brand) 20 gallon upright compressor that I bought 4 years ago. I use it for mostly blow out and occasionally running a die grinder for small spot buffing.

Recently during a longer period of working it I noticed the next day it had tripped the breaker. When I reset the breaker & tried to turn it on it kinda did a "1/2 chug" for a second then kicked the breaker again. I tried this several more times getting the same result until after about 6 tries then a few more the next day it wouldn't respond at ALL and at that point wouldn't trip the breaker either.

I replaced it with a DeWalt 15 gallon upright & figured I would use the old carcass as a reserve tank to give the new motor a break on refills, etc. I hooked up all the fittings & used a modified compressor hose to connect the two. I should also mention, in case it's relavant, that I have 2 out puts on the old compressor that go to the front and rear of my shop (aprox 60-ft apart). The new compressor feeds into the new one & I use the 2 exit ports on the old one for the "OUTS". I even ended up removing the motor on the old one so I could access the ports better for connecting the two compressors.

So I fired it up yesterday and only filled the 1st tank (new one), gave the motor a rest and then flipped a valve I put in to then drain that air into the old tank. After that I re-filled the new compressor & proceeded to go to work for a couple hours in the back using it. When I came back I realized it had tripped the breaker! I tried it again after reset & it came on again fine but now I am very leary about what is going on and fear 2 things: 1-I replaced a perfectly good compressor for no reason or for a cheaply fixable problem and 2- it's a bigger problem with my pannel, breaker, etc?. I should also mention the very first time I tried to use the new compressor with both tanks empty and hooked together it threw the breaker immediately. I dismissed it until the next day & that's when I double checked my work & filled the tanks one at a time.


Help.... :)

__________________
Bill says...

So, Chris, you've got the discharge from the new compressor running into the tank on the old compressor, right?

It doesn't matter to the compressor operation where the air pressure it generates flows to, whether it be a new tank on the new compressor, or through the new one to the old tank, unless you are exceeding the compressor duty cycle. See the Duty Cycle page if you need more info on that.

I find it odd that your new compressor is doing what your old one did before you replaced it.

Kinda sounds like it isn't the compressor at all, huh?

Question, what other electrical devices are pulling power from the same power circuit that feeds the compressor plug?

If there isn't enough power supply to run the compressor motor, the circuit then may try to pull too many amps, and the circuit breaker will pop.

Let's clear this question out of the way first.

Cheers,

Bill

Comments for
Old Compressor wouldn't turn on anymore, bought new one similar issue

Click here to add your own comments

Mar 09, 2012
 Power supply or check valve
by: Gregory

As previously noted the power supply is the first to sort out. First check the line voltage with a volt meter at the compressor and make sure that you have the right voltage. Next read the voltage again as the compressor motor starts. If there is a large difference then you may have a power supply problem. One thing to look for is the length and size of the wiring from the panel to the compressor. You should be using 12/3 wiring which normally can handle up to 20 amps. Both, low initial voltage and/or long thin wiring can cause voltage drop and is not good for the motor. Low voltage causes the motor to draw even more amps and this will cause the motor to heat up.

Also you should check to make sure that the compressor is not drawing in contaminated air that can foul the valves. If air is leaking from the blow down valve (usually near the regulator)while the compressor is at rest, or if the compressor 'chugs' starting up, pops the reset or blows the breaker - it could indicate that the check valve is not working properly and keeping the pump pistons under pressure.

It works this way - the blow down valve opens when the motor switches off giving a hiss as the pressure on the pistons is released. The check valve keeps the air in the tank from coming back and venting through the blow down valve. When the compressor regulator goes to start the motor it shuts down the blow down valve as the motor starts up. If this is working properly then I think you have an electrical supply problem to sort out.
Oct 08, 2010
 Follow up Q
by: Chris

Hi again Bill... Ok so I have some new information. My friend pulled apart the motor on the old one & found several bad bars on the rotor shaft & a lot of carbon build up & general wear. I thought that was odd since again, it was only 4 years old. So the motor was definitely shot & as it was found bad it fried it's fuse. When we replaced the fuse & started it, it burst the fuse again & tripped the breaker.

This still doesn't explain why the new one is popping the breaker too. The only thing I can think is that eventhough both compressors are rated at 15 amps that the new beefier DeWalt draws just a wee bit more on start up than the Kobalt did. Maybe the old one was really close to to exceeding it too & just never went over. It all wor
ks fine & it doesn't happen all the time so I dunno. I'm thinking about running a new dedicated line from the box just for the compressor. Any other thoughts??
Oct 08, 2010
 Final installment?? :-)
by: Chris

Hi again Bill... Ok so I have some new information. My friend pulled apart the motor on the old one & found several bad bars on the rotor shaft & a lot of carbon build up & general wear. I thought that was odd since again, it was only 4 years old. So the motor was definitely shot & as it was found bad it fried it's fuse. When we replaced the fuse & started it, it burst the fuse again & tripped the breaker.

This still doesn't explain why the new one is popping the breaker too. The only thing I can think is that eventhough both compressors are rated at 15 amps that the new beefier DeWalt draws just a wee bit more on start up than the Kobalt did. Maybe the old one was really close to to exceeding it too & just never went over. It all wor
ks fine & it doesn't happen all the time so I dunno. I'm thinking about running a new dedicated line from the box just for the compressor. Any other thoughts??
Oct 02, 2010
 Power draw
by: Chris

Hi Bill thanks for the response. 1st question: yes, new feeds the old & I draw from the old tank. Also should note both the old & new one draw 15 amps each.

On the 20 amp breaker that the compressor on I also have the sign to my store (on a timer) which is only 3x4 w/ just 4 florecent tubes in it & a power strip w/ 3 desk lamps, a bench grinder & 1hp buffer. At best the sign & compressor would be on at the same time, nothing else. Also all of the times it popped the sign was even off. Also the only thing new added to this circuit in 4 years was the buffer and it's been plugged in since at least 2 months prior to having this issue.

A friend is coming up with a multimeter tomorrow to check things out so i'll know more then.

So what do you think?

_________________________________

Chris, when you say "Also should note both the old & new one draw 15 amps each" I hope that doesn't mean that you are trying to run the two compressors at the same time? If so, that's your problem.

What I understand though is that you are only using the tank on the old compressor, and it's not plugged in, and it's the new one that's now popping the breaker on start up?

A 15 amp motor may pull more amps than that on motor start up, hence the capacitor that's there to supply a start-up boost. If everything else is OK, then you may have a capacitor problem on the new compressor, though that's a bit of a reach, to have two compressors exhibiting the same problem.

I am also understanding that you have a 2/2 ball valve or similar in the line from the new tank to the old? When you open this valve, air flows into the old tank, right?

On the old compressor, if the pressure switch has tripped to off, then your unloader valve is probably open, and you may be losing air through that.

Having said all that, since you are experiencing the same problem on two compressors, and the only thing you have between them in common is the power supply, I'm still thinking it's a power supply issue.

Keep us posted, OK?

Bill

Click here to add your own comments

Join in and write your own page! It's easy to do. How?
Simply click here to return to Compressor Blows Breaker