Jon Elson wrote:
(snip)
Ahhh, lucky for you that is a tough VFD or you would have
already smoked it.

So overbuying saved my butt. It never even came up with an error code.

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.

Well, I took out the lower portion, though it looks like the upper switch
is actually riveted into the box. Spliced in some wire to jump the gap
between the two sets of wires. (proper gage, 6-3 stranded copper).
Started it up and it sounds right now. No hesitation and smooth ramp-up.

The pressure switch was already wired into the VFD's control input. I
still haven't found what the pressure switch it set for, but it is at
least 160psi. I know that the control input is wired right because I have
an extra switch wired into that loop and when I shut it off it turns off
the motor. I'll turn it down a ways and see if I can't tweak it to where
I want it.

It was obvious that I hadn't warmed up the shop though, because the
pressure started to head to the redline. I turned it off, and I'll warm
up the shop ahead of the next time, so it can thin out before the pressure
gets too high. Then when it is nice and warmed up, I'll change the oil.

Jon

Todd