Hi, hopefully somebody can help.
I recently had a problem where the heater fan stopped blowing air so I replaced the fuses in slot 5 & 31. Obviously this was a bad move as it nearly started a fire as the fan had seized and the replaced fuse caused it to go in to melt down as smoke came out of all the vents. It took a while but I managed to get a second hand replacement fan (right hand drive vehicle). After swapping out the fan I reconnected the power and the fan came on full blast with no key in the ignition!! After reading up a lot of threads it sounded like I may have fried the power stage resistor. Getting a replacement power stage (part no. 9134933) is harder than flying to the moon! Eventually, I managed to get a second hand one which I was told worked. I have now replaced my power stage with the one I managed to find but the fan still comes on regardless of the ignition being off. I have also noticed that the fan speed slider on the ECC has no effect but it does is make the blue relay (part 9130270) located next to the power stage click. I have ordered one of these relays off eBay to see if it makes any difference. I can get the fan to stop if I pull the plug with the blue wire out of the power stage - I presume that is taking the ground away.

I decided to see what codes were stored and got 124, 411, 414 and 418. I then tried clearing the codes and am now left with 124 and 418 (411 & 414 were old codes for the seized fan). Now I am at a loss as to what to do. Hopefully the relay when it comes will sort the problem but I don't feel confident. I suppose the second hand power stage I bought could also be bad but the person selling seemed confident it tested fine. As these power stages are rarer than hens teeth there may be no way of getting this fixed - perhaps hard wire a switch and just have it blowing full blast all the time but not ideal. It could even push me to sell the car which I don't want to do but can't drive safely with windows fogging up all the time. HELP!!