I have a problem with my Central AC Unit. the Outdoor Unit Does not run when i turn on my Ac at the themostat. I have troubleshot it to the unit outside. The 240 volt breaker outside is good. It is sending to the proper voltage to the unit. there is a contactor/relay in the unit. THe Contactor is not closing. I can manually close the contactor and the Unit runs. there is a blue and yellow wire( seem to be a control voltage wire) coming into the unit that put voltage across a relay closing the contactor. where would my next step of troubleshooting be??? Where does this control voltage come from?

We recently bought an older home which was renovated and has had the garage closed in. There is approx. 1700 sq ft of heated living space. The house has (2) 2 ton each ac units. One in the hallway closet to cool the bedrooms and living room. The other is at the oposite end of the house cooling the garage/bedroom and kitchen areas. Both of these never seem to turn off. The house is always hot. An energy survey by our power company will upgrade the attic insulation. I would like to run new ductwork from the garage side unit which has it's air handler in the attic, near center of the house, to create new runs feeding the rest of the house. Is this a good idea? Is a 2 ton unit enough?? How much distance from the handler box to each drop? Then I'll just centrally relocate the thermostat and hopefully have a much more comfortable home!