Air compressor help (running slow)

[psu927]

Dewalt 80 gallon 2 stage compressor starts but runs slow. Id say 50-75% of normal speed. (when its very cold out it didn't start at all once). I unplugged what I think is the start capacitor, and it didn't seem to want to start at all. If I pull the pressure relieve on the line between the compressor pump and tank, the motor ramps up to full speed. (no load) but drops as soon as load is applied.

This compressor is not very old. I highly doubt there is a problem with the pump. There are 3 capacitors on the motor, would it be one of the other capacitors which I assume are run capacitors? I'm getting a solid 240v even with the compressor running.

 

[Kaizen]

Belt slipping? Try tensioning it a little. Mine only slips in freezing temps and only a little but you can hear the rpm drop


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[psu927]

no the motor speed is slow.

 

[The Cobbler]

unplugging the start cap won't solve anything. as you noted it didnt start at all without it in line.
you mean the pump & motor are turning slowly? the pump oil is perhaps too heavy for the colder temperatures and causing sluggish action.

 

[psu927]

Belt slipping? Try tensioning it a little. Mine only slips in freezing temps and only a little but you can hear the rpm drop


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Well I'll eat crow on this one you got me thinking that I never did confirm the belt wasn't slipping so I just went out and sure enough it is.... tightened it up and it runs like new, so thank you very much.

 

[The Cobbler]

easy fix...
glad it worked out

 

[Bellaireroad]

unplugging the start cap won't solve anything. as you noted it didnt start at all without it in line.
you mean the pump & motor are turning slowly? the pump oil is perhaps too heavy for the colder temperatures and causing sluggish action.

It only gets that cold in Canada[emoji57]


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[marinusdees]

An AC induction motor must run at some multiple of 60, eg., 1800 or 3600 rpm (minus slippage, another subject). If it faces a load greater than it can turn at rated speed, it soon will overheat and self-destruct. Ergo, if it runs at all, it must be turning rated speed. If you hear a slowdown, it's not the motor. Has to be the belt. If it runs for any length of time with any amount of belt slippage, the belt will disintegrate, and may catch on fire.

 

[Kaizen]

Well I'll eat crow on this one you got me thinking that I never did confirm the belt wasn't slipping so I just went out and sure enough it is.... tightened it up and it runs like new, so thank you very much.

Good to hear. Only reason I noticed it on mine was the slight burning rubber smell. Wish they had an rpm gauge to better diagnose issues


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