I know this has been asked before but from reading the other posts I am unsure what my problem is, but here are the symptoms.

I get loads of air flow hot and cool from the dash vents and defrost vents, but I get very minimal air flow from the floor heaters. Any ideas on what door has gone on me?

 

Sounds like the blend door. There is a thread or two on here with lots of good pics.

 

If you've got control of hot vs cool air, then it's the mode door. The blend door controls the air temp and the mode door controls where the air is directed.