Just a qucik update:
My mechanic found that a plug that plugs into the back of the heater had melted slightly and some of the wires were fused together. He pulled the stuck wires apart and plugged it back into the motor and it worked!
Check the pollen filter anyway and also the inlet to it - because the heater motor relies in a good airflow to keep itself cool. Let's be honest something caused the wire insulation to melt and maybe the root cause of the problem is still there and next time could result in a fire. Check all the fuses are of the correct rating or it could also be a faulty switch.
My heater fan seized due to the moisture ingress, the bottom bearing had corroded and that caused the problem.
mine too is the climate control version, it has a different fan to the other type. its easy to drop the fan out, one bolt, then twist and will pull out.
hopefully that is not the cause on your, as they are not that cheap.
I had a heater fan "saga" late last year on my Lag II tourer. A replacement motor from Renault is about £140.00 +vat. Internet breakers quoted me about £90-95. I eventually found a local breaker in West Sussex (removed it myself) who charged me £20 - bargain. Fitted recently and works fine. My initial problem was an overheated resistor pack, cooled by the air flow in the fan housing. I got one of these off the same breaker for £5. The design of these has been changed by renault and to change one you also need to change the wiring connector (the total comes to about £65 +vat).
Go ahead Pras - we all could do with a bit of fresh air - helps clear the mind - but in all honesty I would be surprised if it helped - never seen a blast of air yet fix what seems to be an electrical problem.
I took the plug off again and parted all the burnt wires and made sure that none of the wires touched each other. And the fan started working again. It has been working for a hour now constantly.
And its still working today.
I am finding this problem very weird and unusual!!!!