I have a Rheem A/C unit only downstairs coupled with a Rheem 80% gas furnace. The evaporator coil has a leak that the tech said is not repairable. The units are original with the house built in 1996. I'm sure the furnace has many years of life left. What I want to do is change out the A/C only with a heat pump, such as Carrier's Performace 15 series with matching indoor coil and use the furnace only when it is say below 32 degrees. Do you think I have a chance of this qualifying for the tax credit without changing or modifying the furnace blower? I thought I read somewhere on here that you may have to change the furnace blower motor to a variable speed unit. If it was your house would you go ahead and change out the furnace at the same time even though there is some life left in it?