Kobalt starts fine, but sounds bad at around 70#

by Dick
(San Diego ca)

I have a 60 gal 220 volt that I have used for years. Oil levels and air filters fine. Suddenly now when I start, it runs and sounds fine until about 70#, then it sounds bogged down and makes rattling noise. I started to smell a burning smell so I shut it down.

Comments for Kobalt starts fine, but sounds bad at around 70#

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Jan 20, 2017
Re: Thanks....
by: Bill

From all of us, and contributors, you are most welcome.

Jan 20, 2017
thanks
by: Dick in San Diego

I wanted to thank everyone for the help and update. The capacitor was bad, but I found that the belt seemed a little loose. I tried to adjust but it was at the farthest point. I went ahead and bought a new belt, and voila! That fixed part two of the problem. I am handy and enjoy fixing things, but could not have done it without your help.


Jan 03, 2017
Unloader valves
by: Bill

See the pages about what they are and what they do on this site - linked from the Sitemap page.

Jan 03, 2017
update
by: Dick in San Diego

It is the same sound. But yes, it does go to 130 and shut down without the noise the first time I turn it on. It did not do that before, but has the same sound when it turns back on to refill. What are unloader valves?

Jan 02, 2017
the same binding or run down sound
by: Bill

You say "the compressor restarted it had the same binding or run down sound like it was not getting enough voltage".

This is a new symptom, yes? Originally it happened when the compressor reached 70 PSI.

Can you empty the tank, see if it starts OK then, and if it does and runs up to cut out, make sure the unloader valve functions properly.

Jan 01, 2017
update
by: Dick in San Diego

So changed the capacitor, and started the comp. Ran fine until it reached top shut off. Then when air went down, and the compressor restarted it had the same binding or run down sound like it was not getting enough voltage which is not the case. What else can I look for?
Thanks for the help so far

Dec 30, 2016
Kobalt cap check
by: Doug in s.d.ca

Yes - the first one is at least working, even if *perhaps* not up to snuff.

The second one is defective. I'm guessing that's the run cap.

Dec 29, 2016
update
by: Dick in San Diego

Ok. Model #137603 80 gal, 4.5hp. It has two capacitors. A start and a run. Took both out and put the meter on. On one of them when I set it on ohms and put the leads on it registers about 9 volts and decreases. When I swap the leads it starts out negative and heads to positive. On the other, in one direction I get nothing. Just OL. When I swap the leads I get negative 277. I am not sure which is which, but that one seems to not read correct. What do you think?

Dec 29, 2016
starts fine
by: Doug in s.d.ca

Depends on the model.

But if it has capacitor(s) you should start by checking it/them -

http://www.about-air-compressors.com/testing-capacitors.html

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