How can I clean out the heating and ac ductwork in my ranch house?

Call a duct cleaning service.

It is not practical to try to do this yourself, there are special attachments and tools that need to be used to do it correctly.

I guess if you get enough extra extension tubes, a few rolls of duct tape, you might be able to clean some of it, as long as you duct tape holds, and you don't loose parts deep in the duct work where they can't be reached.

I say have it done by a professional.