Hopefully you'll find that the cable is kinked behind the control knob, not broken.
Bad news is you need to first remove the console around gearstick to get centre console out to carefully straighten the cable.
You can check both ends of the cable by first removing your radio and looking up behind control knob with a torch for one end. Other end is connected to a lever affixed to centre housing to the left(and above) of the clutch pedal. You'll need to have your head in the floor well to see it!
Make sure you can move this lever or any fix will be very temporary(try and use your other hand to move control knob at the same time to avoid possibility of further damage or kinking)! Alternatively, if you wish to bodge the heating full on, the cable at the lever end can be removed easily. Pull it way from the lever towards the clutch pedal and then come up with a way of sticking the lever in the warm position(it naturally springs back to cold).
I'm reasonably certain that you'll find your cable has developed a nasty kink behind the control knob, like mine did, which means it isn't opening the flap enough to let hot air through the system.
The cable attachment to the control knob looks very flimsy, so it will need to be straightened with great care but I managed it yesterday and the fix worked fine.
Bearcub, November 2008
