On Sat, 17 Sep 2011 10:21:35 -0700, wrote:

I'd say the embarrassing thing here is that you did not check for
voltage
at the unit as the first step. It doesn't get any more basic than that.

Actually, I did. I checked voltage at the fuses right next to the A/C
beforehand, and 'both' leads were the same 120volts! I thought that was
weird, as there were 0 volts between them! (Now, I know, the circuit
breaker must have been broken inside to allow that!). But I didn't know
then that that's the way this thing worked (as I couldn't comprehend it
so that's why I called the AC guy in).

Once the AC licensed technician told me the voltage was fine, I
'assumed' (yes, that's my mistake) he was right and therefore, the 'same'
120 volt line must be split up on the white and black lines going into
that AC-only fuse panel. How wrong he was and how wrong I was to trust
him.

A week or so later, when we finally had concluded the original licensed
technician was either lying or outright incompetent, we measured again,
and guess what? It was 28 volts at the one lead, and 120 across, and
something like 85 volts between them!

By now, I knew enough to go to the circuit breaker, where I saw the same
thing; and then, removing the outgoing wires from that circuit breaker, I
could finally see the 0 volts on one lead and 120v on the other (with 120
on both leads going in).

Once the breaker was replaced, the normal 120 on each and 240 across
resumed, and, the A/C unit worked (which never had a problem in the first
place!).