get your make and model and search google for the manual.

in the meantime, the one blower may be to move the air to the house.
the other little one may be to blow the flue gas up your chimney.

in buffalo ny put your gas billing on balanced billing, unless you make
more money in winter.

general furnace article not repair at:
http://www.bobvila.com/ArticleLibrar...ForcedAir.html