Course you can change the heater matrix on a sapph, you have to remove the lower half of the dash, disconnect the clutch pedal (otherwise the matrix wont slide out) and then tug like hell from the drivers foot well, whilst applying the brake pedal enough to slide the matrix all the way out. Like I said above, it's a pain in the arse job to do, and will give you a bad back for weeks, but once it's done, you won't have to worry about it for another 10years, unlike if you try to blow the crap out with a garden hose!!!!!!

Steve