I have a Bryant 90% furnace around 10 years old that keeps showing a limit circuit lockout code (#13). The heat shuts off but the blower keeps running. I have reset it several times via the button located inside the unit on the top right, but the top of the unit seems to get almost too hot to touch and it happens again after 24 hours or so. It runs on propane. Any suggestions are much appreciated since I am selling the house in a little over a week (and am purchasing a home warranty policy for the buyers that should pay for any issues) and hate to have to spend a bunch of money on it now. Thank you!

If it is a 90%, it has 2 plastic pipes. Make sure either pipe isn't blocked, I had a wasp nest in my exit pipe. Also make sure the filters are clean and not obstructed.