I had this problem and found this thread.
Paul was spot on - down by the clutch pedal you will see two plastic cogs - one of mine was one white, the other black - this is what moves when you turn the temp control for the fan (the wire in mine had broken) so I turned the smaller one (below the bigger one) and it turns the bigger one and hot air at last!
I think I will leave it at that - no need to fix the steel wire that connects the cogs to the dashboard control for me
Paul you are genius !!!!
Tony
September 2008