I had a Carrier Weathermaker 8000 2-Speed gas furnace installed in my attic 5 years ago. I let the contractor talk me out of going with the variable speed model and am disappointed with the result. I have friends that have since gone w/ variable and realized much more even heating/cooling and much quieter operation, humidity control, etc. My home faces South w/ large windows and in the winter and summer I cook on the South side and freeze on the North. I am now at the point where both outside units (we have 2 systems) are going and I'm looking at definite replacement of both outside units and the basement furnace (15 years old). I might also replace the 5 year old Weathermaker 8000 2-speed just to go with a variable model in the attic at the same time, but am wondering if there is a way to convert it to variable speed (maybe a different fan and/or control module?) before I send it packing... Thanks!

We have flexible air conditioning ducts above a sheetrock ceiling. I have not used the system for around half a year. We have a strange smell emanating from the ceiling, which seem to be coming from the air conditioning vents, but I am not sure. Is the smell related to the air-conditioning system? How does one isolate the source? How does one deal with the problem? Thanks.