"Jon Elson" wrote in message
...
Todd Rich wrote:
Randy wrote:

Todd,
open the electrical box on the compressor when you start it, and
watch what is going on in there. That sound seems to me to be the
contactor in there chattering. With the VFD running the motor you
should not even need that contactor connected.


Where exactly should I be looking?

http://i166.photobucket.com/albums/u...comp/comp1.jpg
http://i166.photobucket.com/albums/u...comp/comp2.jpg

Should I remove the whole lower Allen-Bradley unit?


yes and the top too, you need none of it just remove the whole thing from
the compressor...

I'm afraid I'm really not that up on what is in that box.
Ahhh, lucky for you that is a tough VFD or you would have
already smoked it. Just bypass ALL the stuff in there, wire the
VFD straight to the 3 motor wires. The pressure switch should
be wired to the VFD's control input.

Jon

Bingo I assumed that you had trashed all that VERY old AB stuff in that
box.

Remove it and let us know if it stops that nasty noise.

William....