Air compressor will run with help but won't start by itself.......capacitor bad?

[Cranky]

Here's a pic of the motor....I'm guessing this is the start capacitor under the cover? There is a smaller cover and I'm guessing it's a run capacitor? The pic he sent shows two....one larger cover and the other is smaller but looks like the pic is too big to get it all in here This off of a friend's compressor and I haven't laid hands on it. I'm a bit lite on electrical stuff but have replaced capacitors on AC units before but never messed with electric motors like this. He said it'll run if he helps roll the pulley and it runs like it always has but won't start on it's own.

 

[1 Wild R/T]

Probably the capacitor but it could have a bad check valve or relief allowing pressure in the pump when it's starting... It should drain the line from the pump to the tank... There is a one way check at the tank inlet & the pressure switch has a bleed line that it should drain when the pump shuts off..

But it does sound more like the capacitor..

 

[1967coronet]

What wild said,
have him check the capacitor for bulged / swelled ends
Damn things most times do that when they go bad.
Plus remind him that the capacitor retains a charge.

 

[6872n73]

I would certainly check the capacitor. my multi meter has a capacitance reading that makes this easy.

 

[1 Wild R/T]

Plus remind him that the capacitor retains a charge.

Shocking!!!!

 

[MarPar]

Check the tension on the belt(s) too.

 

[Cranky]

Probably the capacitor but it could have a bad check valve or relief allowing pressure in the pump when it's starting... It should drain the line from the pump to the tank... There is a one way check at the tank inlet & the pressure switch has a bleed line that it should drain when the pump shuts off..

But it does sound more like the capacitor..

If the capacitor is bad, will the motor start with no load. I mentioned to try that and will ask him if he hears the line bleed off. I can hear it pretty easily on mine.

What wild said,
have him check the capacitor for bulged / swelled ends
Damn things most times do that when they go bad.
Plus remind him that the capacitor retains a charge.

So far I've done 3 on AC units....they all looked fine but tested bad and yeah, told him they hold a charge. I've told him to pull the covers and take a look but haven't heard anything back yet.

Shocking!!!!

I'll tell him to check that by sticking his tongue on the terminals

 

[1 Wild R/T]

I'll tell him to check that by sticking his tongue on the terminals

I like the way you think...

 

[MarPar]

FWIW...I ran into problems with my compressor a while back. Changed the capacitors and no difference. It turned out to be the belt.

From the Quincy Manual...

 

[Cranky]

FWIW...I ran into problems with my compressor a while back. Changed the capacitors and no difference. It turned out to be the belt.

From the Quincy Manual...

View attachment 1655392View attachment 1655393View attachment 1655394View attachment 1655395

What was up with the belts?

 

[MarPar]

What was up with the belts?

They was oooooold, stretched and slippin. They had to have been at least 20 years old by the time I was gifted it in 2006.

Now I have a happy little compressor again. lol

 

[MarPar]

Found my thread...

Quincy Model 219-39 Air Compressor

Gents! Need to tap the vast wealth of knowledge here to try and repair my old Quincy 219-39 air compressor. Now, I want to fix this olde girl and keep this setup. So to everyone who'll say just buy a new one, thank you, but that is my LAST resort and will cross that bridge if I get there. She...

www.forbbodiesonly.com

Lots of shenanigans, but problem solved. lol

 

[eldubb440]

I bet my belts are the originals...... 1982

and seem to have misplaced my belt tension gauge

 

[HEMIB]

If it starts OK with an empty tank probably the head unloader valve if not the start capacitor or the centrifugal start switch is not closing when the motor stops.

 

[1967coronet]

Some have separate start and run capacitors , some motors have a combo capacitor. If it's got the separate ones the rolling start probably would.
Another thing that will put a big load on them is plugged air filter/intake.
Capacitors are not to expensive , Ace hardware ect should be able to match one up for him if needed.

 

[Krooser]

When replacing capacitors discharge the capacitor by grounding the hot to ground without touching the hot side.

You must use a new capacitor with at least the same voltage rating as the original...higher will work, too.

The microfarad rating can be higher, too but never lower.

On guitar amps I replace 400v rated caps with 500v or higher.

A 100mfd cap can be replaced with a 150mf without issues.

 

[MarPar]

@Cranky

 

[Krooser]

BTW...I will be doing an air compressor video on YouTube this week. I have to change the pressure switch hoping that will get mine back up and running.

It's hell not having shop air...

 

[toolmanmike]

If the capacitor is bad, will the motor start with no load. I mentioned to try that and will ask him if he hears the line bleed off. I can hear it pretty easily on mine.

So far I've done 3 on AC units....they all looked fine but tested bad and yeah, told him they hold a charge. I've told him to pull the covers and take a look but haven't heard anything back yet.

I'll tell him to check that by sticking his tongue on the terminals

I bet @kiwigtx will know

 

[Sam69sat]

I have a compressor that would start sometimes and hum other times. It would usually trip the breaker after a short time. Turned out to be a dirty start switch?? in the motor. Opened the motor, cleaned the contacts and it's worked ever since.