I have wired my window a/c but can not get it to opperate. I have 12-2 wire running to a split (two narrow) 20 amp breakers for 220v. The black and white are both hooked up to the breaker and on both gold screws for the 20 amp 220 volt outlet. There is no place for a common so I used 12- 2 instead of 12-3. However the system does not turn on. Any suggestions?