I have a conquest 90 furnace that just doesnt seem to cut the mustard. I notice in the cold snaps that the thing doesnt operate any better. they advertise it being a 2 stage so when it gets colder it kicks in second stage to help keep things warm . It seems to me this is not happening. I also notice the air coming from the furnace doesnt seem all that hot. I mean as long as its not down around zero everything comfy. But when it gets real frigid it just seems not to perform all that well. I just wonder if there are some things I need to look at. The furnace is about 4 years old. thanks if anyone can shoot me some input.