Air Compressor Problems

The last couple of weeks my air compressor would periodically trip the circuit breaker.
Well today it did it again only this time it wouldn't start back up. So I removed the drive belt and tried the motor. It seemed to spin freely and even for along time after I turned the power back off.
Next I tried to turn the drive wheel on the pump. I could not get it to turn by hand until I drained all the air out of tank. At this point I turned it over slowly and could hear the compressor drawing in air. Oil level is good, air filter is clean, etc.

When I hooked it back up and flipped the power on it didn't sound as loud as usual and then began to periodically slow way down, then speed up.
I recorded a short video on my cell phone so you could hear it but have no idea how to post it on here.
 
I had something similar when my “unloading” valve failed. It places a huge load on the motor when it starts.

Hope this makes sense.

Don
 
Yes a start capacitor will have the symptoms of starting and tripping the breaker. But being you took the belt off and your pump feels abnormal to you I’m not sure.
 
Yoiur compressor motor may have a start and run capacitor. Pull them off and take to a electric motor shop and let them check out. Or look up on You Tube and you can check them.
 
Thanks guys.
I ordered a new pressure switch today with a new unloader valve.
When I shut the compressor down, I could hear air leaking from the pressure switch area, so hoping that might be the problem.

I have an volt/ohm meter and will check the capacitors while I wait for the pressure switch to arrive. Yes, with the power off.

Amazing how fast this shut down my progress. I was using my air drill to remove the hundreds of spot welds on the trunk floor pan when it ran out of air. Sure enough the breaker had tripped, so I reset it and could hear it turn over about twice and then a humming sound until the breaker tripped again.

It's only 15 years old and used nearly everyday, so what could be the problem? LOL
 
when the compressor shuts down your supposed to hear air pissing out the psi switch. thats what it does. it should eventually stop though. it releases that pressure in the line and pump head so it can start 1 rotation not under load. take a look at the capacitors. a bad one will usually be swelled up, charred or leaking. if your psi switch does let the psi release then second would be caps, third would just be motor windings and you should just get a new motor. we just went through this on my dads 7.5 ingersoll. it came with a weg motor. mine had a weg also and both of those motors i have had nothing but issues with over the years. mine would burn through start switches every 3 mos. my dads would chew up caps like crazy. both of us just got so tried of messing around with them we took both off and just replaced them with good leeson motors. knock on wood, not an issue since with either compressor.
 
It sounds to me as though your unloader valve has failed. Capacitors are cheap, just get new ones and eliminate that possibility. mark them and take them off to get replacements. the start and run caps are usually different microfarads, the way they are sized. If your compressor is 15 years old and been used as hard as I bet it has, They have discharged 1000s of times.
 
when the compressor shuts down your supposed to hear air pissing out the psi switch. thats what it does. it should eventually stop though. it releases that pressure in the line and pump head so it can start 1 rotation not under load. take a look at the capacitors. a bad one will usually be swelled up, charred or leaking. if your psi switch does let the psi release then second would be caps, third would just be motor windings and you should just get a new motor. we just went through this on my dads 7.5 ingersoll. it came with a weg motor. mine had a weg also and both of those motors i have had nothing but issues with over the years. mine would burn through start switches every 3 mos. my dads would chew up caps like crazy. both of us just got so tried of messing around with them we took both off and just replaced them with good leeson motors. knock on wood, not an issue since with either compressor.
Mine is a WEG motor as well. However, I have had no issues with it up until now.
 
Yeah I’ve changed a fair amount of start capacitors on compressors and lots of other equipment. As Jim said sometimes you can even tell they’re bad visually by being swollen or leaking. Or as stated not releasing pressure. On the bright side sounds like an easy repair? Gotta be optimistic right?
 
Okay, I dismantled the problem areas.
Here's my run capacitor and it doesn't look healthy :
Air compressor run capacitor damage.JPG



Then I found a small leak in the tubing the runs from the check valve to the pressure switch:
Hole in tubing for Air compressor.JPG


The check valve has also seen better days:
Air Compressor Tank check valve.JPG


Ordered new capacitors and check valve today. Hoping the local hardware has the 1/4" aluminum tubing I need.
 
Oh my!...... now that's a compressor who has given its all over the last 15 years. She'll be good as new very soon.

Don't forget to change the oil and air filter :)
 
Um, yeah that capacitor is well done lol. Might as well give her a tune up while she’s apart I’m sure she deserves it. How’s the start capacitor look? Also on the tubing…you can probably get some 1/4 brake line from the parts store. The nickel copper is super easy to work with.
 
Got the parts in today and started installing them.
Pressure switch, tank check valve, new copper tubing, all no problem. Turns out the capacitor's I ordered were too large in diameter to fit.
The place I ordered them from took them back and even paid the return shipping.
Found the ones I need and of course they are four times more expensive. :rolleyes:
Now more waiting!
 
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