guys, guys, guys - you are worrying over nothing - the smell is caused and created in the AC condensor, it is the matrix where the air is cooled and as a result water is condensed out of the air ( noticed the puddle on the floor before?)
As the condensor matrix is normally always wet it promotes the growth of fungi/ mold etc, it is this which causes the smell.
you have 2 ways to stop this - get the smoke bomb type of cleaner, you put the AC on recirc, close all the windows etc and then activate the canister it is drawn thru the matrix and kills the fungi and leaves ur car with a nice smell.
other option is to place a tube up the AC condensor outlet ( under the car) and spray in a special foam that also kills the fungi.
Its Steves lucky day as i happen to "have" a can or 2 at my disposal so when im back in the Uk next week ill post it to you - i Have tried to use it on my IS but the Ac outlet pipe took a few 90 degree turns so i couldnt get the pipe in all the way.:(
cheers rob.