I have a 93% ducane furnace that is 10 years old. When I moved in last year I noticed the furnace stays lit for 50 seconds. I checked my hoses to the inducer housing or motor and they were not clogged- I just unhooked the house from what I guess is the heat exchanger and there was some rust. I took out the condensate trap and there was a lot of rust. Is this rust a huge problem? I also noticed a cap was missing on my inducer housing and it looks like exhaust could be escaping- hopefully sealing that will help, but before I spend more time on it I want to make sure there isn't a serious problem
a lot of rust could be a problem. the "heat exchanger", the part that attaches to the furnace is the evaporator coil for A/C. it should look like a large V with a bunch of aluminum fins and then the edges will have curls of copper for all the pipes that run through the fins. the metal will eventually start corroding and that corrosion will eventually break off into the pan and flow into the condensate drain and into the trap. it could mean that your coil is on its last legs and will eventually spring a leak if it isn't already slowly leaking.