XSeries-forum

When I turn the blower fan up, I get a strange damp/ musty smell in the X, both with and without aircon on, that appears to be more pronounced when it's been wet.

I'd almost say it smells faintly of chemical camping toilet.

Anyone ideas why this is happening? Or where I can start to look?

May be mould in the ac. Spray Neutradol into the air intake under the bonnet. Replace cabin filter as well. Also check there are no leaks around the filter housing.

Both are easy to do.  The filter is a 5 min swap job and ECP sell them.  I chose to use the activated charcoal version.  Cheaper from them rather than BMW!

Cheers, I'll give that a go.

Am I correct in thinking the filter is under the scuttle tray on the near side in a black box?

It's within the scuttle tray under the cover with the finger twist 90deg latches.  Runs pretty much the full width of that tray.  Video linky below:

http://youtu.be/evZOk221Ht0

you can also buy a 'bomb'. Here is link but I'm not endorsing that product, its just an example and others are available
http://www.bilthamber.com/air-con-bomb-citrus

You switch on the blows to full, activate the bomb (instructions on it but basically just press a button on top), sit it on the floor of the car and close the doors and let it do its stuff ten/fifteen mins as I recall. it gets into the system and kills the bugs basically.

I've done it a couple of times over the last six years. very effective and low cost