Hi guys, bringing my car back from the MOT today i turned the heating to hot and turned the blower on and the whole car misted up within a minute or so. There is no damp in the footwells at all. Does this sound like i need a new matrix? or is there anything else that could be causing this?
What is the matrix like to do on a classic,?

 

Exactly the same thing happened to me a couple of weeks ago on my 1999 classic. Tried sealant but it only lasted a week before the steaming returned.
Only option is a replacement matrix, £250 from Subaru or around £20 on ebay if you are lucky.
Replacing the matrix means a dash removal and refitment, which is around 5hrs work.
Hope this helps, although it's probably not what you wanted to hear.