ok, courtesy of the instructions from bluemonkey here
, I got the Climate Control back working on my Scenic today. Its a real pain in the nuts to do, and my arm is scraped to bits but definitely worth persisting at.
Renault quoted me ***8364;500 to fix this - 200 for the part and 300 for labour! I found the part here
for ***8364;50, its exactly the same brand as the one I pulled out of the car, and was able to access the unit (variously called a rheostat or actuator) using the method described at the start of this thread. Still need to replace the pollen filter so it doesn't fail again, but that seems straightforward enough.
My tips for anyone trying this - tie string to any screwdrivers or hex keys you are using as if you drop them behind the dash, you won't get them back. Also use masking-tape to attach the screw to the head of the screwdriver/key when you are screwing it back in.
here's a photo of the original unit, in situ and then removed: