# My compressor died today



## alloy (Mar 10, 2021)

I've got a 22.5 cfm 7.5hp 220v single phase two stage compressor.  Ran it yesterday for 6-8 hours and zero problems. Today it won't start.

I'm not too good with electrical. I can run wires, add a circuit, install a phase converter (with help) check voltages.

It has a mag starter on it.  I've checked incoming voltage all the way from the breaker to the compressor.  Seems fine.  The pressure switch is closed, power to and out of it. 

The mag started doesn't engage.  I can manually push it in and get voltage to both legs of the motor but no go.  Even tried putting voltage directly to the motor bypassing the mag stared and still nothing.

Thankfully I have a backup compressor, but it's half the cfm and my pressure blast cabinet keeps it running constantly.

I've found a replacement motor for $535 with free shipping  which isn't bad, but before I buy it I want to make sure I'm not missing something.

HELP!!!


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## Reddinr (Mar 10, 2021)

Does it have a starting capacitor?  That could be blown.  <$20 maybe.


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## markba633csi (Mar 10, 2021)

I would check the connections right at the motor terminal board and look for burned or melted lugs or wires
It's possible a connection inside the motor let go but do some easy checks first.  Check connections to capacitors too.
If there is no hum at all then it's probably a broken connection not a bad capacitor
-Mark
The centrifugal switch in the motor may be shot but you might be able to replace it for much less than a new motor


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## alloy (Mar 10, 2021)

It has three capacitors.

Connections  look good.  Nothing loose, nothing burned.

No hum, nothing at all.

Actually after blowing up the pic I see corrosioo a couple of the spade connectors on the the capacitors.   I'm going to clean them and see if that helps.


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## Gaffer (Mar 10, 2021)

I have a Campbell Hausfeld with the same specs as yours. On my motor are two semi-circular plates attached by screws. They house the start and run capacitors. If you have a meter it would be a pretty simple troubleshoot to ensure you have proper voltages, and specifically where you are losing the connection.


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## JimDawson (Mar 10, 2021)

Press the little red button just below the starter contactor, the one on the overload


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## Gaffer (Mar 10, 2021)

I believe those are your run caps. Do you have another cover, possibly on the side of the motor? That would be your start cap. Caps can be tricky by looking fine but they're not. Your better meters will read capacitance.


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## Gaffer (Mar 10, 2021)

Good eye Jim. It does appear to have tripped.


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## Reddinr (Mar 10, 2021)

It looks like the two caps on the right are motor start caps and appear to be wired in parallel which doubles the capacitance.  Probably needed for the larger size of the motor.  The metal can one is likely the motor run cap.  Much more likely that one or both the motor start caps is gone.  They can be tricky to measure even with the right meter.  It is a cheap trial and error fix to just replace both of  the motor start capacitors (if your reset button push didn't fix it).


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## alloy (Mar 10, 2021)

One of the first things I tried was the reset.  

Just pulled the wires on the caps and reseated them, nothing.

If I push the mag starter there is voltage going to the caps.

I guess I don't understand why the mag switch isn't engaging.


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## alloy (Mar 10, 2021)

Both caps are the same.  I'll start looking for some.


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## alloy (Mar 10, 2021)

I see capacitors on amazon, but the numbers don't quite match up.




__





						216-259 uF x 220/250 VAC - BMI Start Capacitor # 092A216B250CD6A - Made in The USA: Amazon.com: Industrial & Scientific
					

216-259 uF x 220/250 VAC - BMI Start Capacitor # 092A216B250CD6A - Made in The USA: Amazon.com: Industrial & Scientific



					www.amazon.com


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## JimDawson (Mar 10, 2021)

Did you test the voltage across the incoming power wires or to ground?

The caps should have nothing to do with the mag starter.  But I don't know why it didn't run when you pushed the mag in.  It really sounds like an incoming power problem.


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## Reddinr (Mar 10, 2021)

The caps you found look similar enough to work.  $30 to me is a low cost thing to try but not guaranteed it is the only thing wrong.

Reasons a motor starter won't pull in:
  Motor starter coil burned out.  
  Overload is tripped  (the contactor should pull in once it is reset, if just for a short time if still overloaded)
  Wiring problem in the contactor coil circuit.

By pushing in the contactor manually, even with the above problems, the motor should start.  That likely means you have a starting capacitor problem or you have a motor that has gone bad.

BTW, a starting capacitor problem can be tied in with the motor's centrifugal switch being stuck.  At the end bell of the motor is a switch that opens once the motor spins up.  If it is stuck closed it can fry the motor start capacitors.   If the switch is stuck open then the starting capacitor is never put into the circuit and the motor won't start to rotate.


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## FOMOGO (Mar 10, 2021)

Looks like the sart caps have been leaking. I would replace both. disassemble the mag starter and check the contact points. You might be getting voltage reading, but not enough amperage do to burnt points to kick the motor in. Mike


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## alloy (Mar 10, 2021)

Jim you hit it on the nose.

Checked across and zero. But to ground was 119. Went to the breaker and same thing.  Pulled the breaker and the lugs on the breaker box were 236 across, but out of breaker zero.  Had another 40 amp breaker next to it, swapped them out and it runs.  Breaker must have went bad.  Never saw that before.

If everyone thinks I should replace the caps I will.  Just need to get the correct ones.

Thank you everyone.  You guys saved my bacon today.


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## JimDawson (Mar 10, 2021)

If the old caps are leaking, then it wouldn't hurt to replace them.


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## alloy (Mar 10, 2021)

I'd rather replace the caps now at the time of my choosing rather than when they fail and have to do this all over again.

I've found some on amazon and other places but the numbers don't exactly match up.

Do the numbers have to match exactly?

I'https://www.amazon.com/250-Grainger...baldor+ec1216c06+250vac&qid=1615428792&sr=8-2


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## tq60 (Mar 10, 2021)

Troubleshooting 101...

Always check power first.

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## JimDawson (Mar 10, 2021)

alloy said:


> I'd rather replace the caps now at the time of my choosing rather than when they fail and have to do this all over again.
> 
> I've found some on amazon and other places but the numbers don't exactly match up.
> 
> ...


Most important is the rated voltage, then the MF value should be close, then the physical size


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## alloy (Mar 10, 2021)

Ok, the one I linked to on amazon says:

Supersedes all , 216 - 259 uF which matches the one I have,

and 220/250 vac

+65c
​Mine is 250vac and +65+

Am I reading this right that it will work with 220-250vac?

Just want to make sure before I order them.


"Troubleshooting 101...

Always check power first."

I did, just didn't know to check leg to leg, not just leg to ground.

Learn something new everyday.


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## JimDawson (Mar 11, 2021)

Looks like that will work.


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## alloy (Mar 11, 2021)

Just ordered them.


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## markba633csi (Mar 11, 2021)

Yep always check the obvious- "is there gas in the tank?"
Glad you got it
-M


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## alloy (Mar 11, 2021)

Didn't check for gas, the gauge said full 

Same with voltage,  had 119 to ground both legs  but didn't realize I had to check leg to leg.

When I built my phase converter I checked leg to leg to set the voltage taps on the transformer, but had no idea you could use leg to leg as a diagnostic tool.

Like I said, learn something new every day.


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## alloy (Jun 22, 2021)

Well the knowledge of checking leg to leg came in handy yesterday.  I ran my manual mill yesterday morning to do a small job, but then in the afternoon it wouldn't run.  Checked voltage to ground both legs at 117v, and leg to leg was zero.  Replaced the breaker and it worked.

This is the second circuit breaker I've lost in the last few months.  I'm using the breakers for the machines to turn power on and off between use.  I guess I'm wearing them out that way.  Thankfully I had an extra breaker I stole from my small air compressor.  Next time I go to town I'll buy two of them, one for a spare.


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## fixit (Jun 23, 2021)

The pressure switch controls the Magnetic contactor. Either there is a fault in the pressure switch or the coil is faulty in the contactor


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## tq60 (Jun 23, 2021)

Circuit breakers are not load controllers.

DO not switch under load. 

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## alloy (Jun 23, 2021)

tq60 said:


> Circuit breakers are not load controllers.
> 
> DO not switch under load.


I don't switch the breaker on the mill under load.  The compressor leaks down so on startup it is under load, but I never switch it off while running.


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## alloy (Nov 8, 2021)

Ever since I replaced the capacitors a couple of items a day the mag started kicks out the reset. Did it one day when I was milling a transmission housing.  I have a air power draw bar and apparently the air pressure was getting low and didn't notice when I put an endmill in and the tool pulled out of the collet and dug into the part.  Thankfully I caught it and was able to save the part, but just barely. It also pops the reset when I'm using my bead blaster.

Befoe I changed the caps it didn't do this ever.  What changed?


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## JimDawson (Nov 8, 2021)

You really need to check the amp draw on the motor.  If the amps are in a reasonable range, then try turning up the amp setting on the overload relay.  That's the yellow dial on the overload.

Check the amp draw with a clamp meter.  https://www.amazon.com/s?k=clamp+me...refix=clamp,aps,145&ref=nb_sb_ss_ts-doa-p_7_5


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## alloy (Nov 8, 2021)

Thanks Jim.

I beleive I have an old meter around here somewhere.  I'll try and dig it up and see what it says.


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