Air Conditioning - need to buy new central a/c, s. calif.

i have an 18+ year old carrier central a/c unit on top of my house. I turned on the heat one day and it wouldn't work. the repairment said i needed a new "electronic start", for quite a chunk of money, and could maybe get a couple of years out of it, or, buy a new unit. a new, 3-ton unit is quite a chunk of money. Two bidders offered 1,(last year's cheaper) Rheem and 1, Carrier (many models to choose from) and didn't look in the attic or mention anything about new ducting, permits or R22 vs R410 refrigerant. Sears came out and spent a lot of time, measured and looked in the attic, mentioned the permits, advised new ducting, testing of new ducting and permits and explained R22 ends and R410 begins in 2010. Also wanted twice as much. How important is that new ducting, the testing of the new ducting and permits? thank you.

Ask your friends and family who they use and trust and get more quotes.

I would go with R-410a, also have a load calc done"manual J" any reputable company will do this to properly size the equipment. Having the duct work checked is also a good idea.