Cleaning coach furnace

[bbohn]

I like to do preventive maintenance as much as possible. But I find nothing that tells me how to clean and service the furnace. Any hints? I have an 04 DS and have never done anything to it. It just keeps purring along. But I worry.

["007"]

If it isn't broke why fix it.
Mine has been working for 8 years without a hitch.
I do check for any foreign mater in and near vents input and output tubes and just check for cleanliness around housing with the face cover off.
Did have a mouse get fried and head wind up in burner fan so did have to clean out that mess but over all its never failed us.