Why does my air compressor motor run fast then slow

by Rocky
(Fort dodge Ia.)

I have a devilbiss 2 Stage 5 hp compressor. while it's running compressor sounds like it goes faster then it slows down for a couple seconds then goes back to regular speed. it either slows down or quiets down.

---

Bil waffles...

Howdy Rocky. Welcome to about-air-compressors.com and thank you for visiting and writing in.

Hmmmm, that's a tough one.

What could affect the motor speed?

Option 1: If you have current fluctuations that would affect motor speed. If you think of electricity as electric gas for an electric motor, if you reduced the amount of "gas" to the motor, the motor would slow.

Option 2: Possibly the check valve into the tank is causing some flow problems, and if it restricted the flow of air into the tank, then the back pressure could slow the motor. Not likely, but possibly.

I'd go with option one. Maybe something else is turning on while your compressor is running, pulling power from the supply to the compressor, to feed the other item when it starts up?

Cheers,

Bill