The air in my dad's house is not cooling. Tempstar 13 SEER R410a split system a/c condensing unit was put in in 2011 along with a bryant 2 stage gas furnace (BTU--78,000 high; 50,000 low). Coils not replaced (date is 1996 or 1997). Installers said the compressor and coils are shot and although compressor is still under warranty, the labor for both and cost of coils will be $4200.00); another company tells me that the blower on the furnace is not sufficient for the 5-ton condensing unit and everything needs to be replaced (furnace, condensing unit, and coils) for about $6300.00. I don't what to believe, shouldn't the company who installed initially have put in the right size units? The new condensing unit uses the new refrigerant and the coils use the old... there is no adaptor between the two... shouldn't they have done this? I appreciate any accurate information you can give me.

Coils should have been replaced, particularly with 410a.