Proper Circuit for 220 A/C

Lot's of discussion here. I have discovered, since the original post, that the wire is 10-2 w/g. I have decided to consult with an electrician. As soon as I get an answer I will post it. Thanks for all your input.

True dat, Mulder. No one seems to have considered that you said in your second post,

"I wired up my cooking stove, and most of my basement."

Does this mean that you have used the first mentioned "dble pole 30Amp breaker, 12/2 w/g wire [which you now believe to be 10/2], as a circuit that supplies "my cooking stove, and most of my basement" plus you want to add the window AC on to that same circuit?

If so, that is a definite no no.

I also would like to know, Mulder, "is the truth really out there?"

12/2 is not rated for 30 amps so you cannot have it connected the current breaker. Also is the new Central air unit 220 V 2 wire or a 220 V 2 wire (with neutral) if its 3 wire you'll have to go buy new cable and run a new circuit. If the nameplate on the unit states it will only draw a max load of 9 amps you can safely use 14/3 on a 15 amp breaker to feed it.

As always consult you local code as requirements are different for location to location.

GL