1. Bryant Serial Number

My 90plus High Efficiency Bryant furnace is costing me my life savings. When the furnace kicks on if set at 68 degrees and has dropped on thermostat around 2 to 4 degrees it runs for 20 to 30 minutes every time to get up to 68 degrees. I know this is not normal. I have had repair man out to check it several times found nothing.

Bryant Serial Number

I wonder if it is the blower or what is the problem. My model number is 0997x37197 any help would be great.