I have a Dunham Bush SapcePak Blower coil unit model number ESP3036 Series C. It is hooked to a Dunham Bush outside ac unit that is Model 3.6 and is a 3 ton unit using 230 volts ac 60 cylce 1 phase. My ac unit has gone bad but the blower unit is still good. I was told that I can hook and 12 and below Seer rated unit up. The best would be a Seer10 rating. Is this true? My home has the small high CFM 2inch duct work and I don't wish to change that. I have found some 10 Seer units but am not sure. thanks for any input.