I replaced the heater matrix this week in my 2002 R50. Symptoms were :-
The heater matrix is right behind that plastic panel so if it's getting warm you should be able to feel it without removing the panel.
I've left the panel off mine for the time-being just to make sure there are no leaks before I put the panel back and the matrix gets too hot to touch (as you'd imagine).
I have read somewhere that in some cases, on removal, the matrix appeared OK but is clogged up so a flush was all that was required.
- coolant loss (slow but consistent),
- poor heating (would kind of feel warm if the fan was low but on higher speed felt cool)
- very damp on the inside of the windows (especially cold mornings which is why I just did it!)
- musty smell
The heater matrix is right behind that plastic panel so if it's getting warm you should be able to feel it without removing the panel.
I've left the panel off mine for the time-being just to make sure there are no leaks before I put the panel back and the matrix gets too hot to touch (as you'd imagine).
I have read somewhere that in some cases, on removal, the matrix appeared OK but is clogged up so a flush was all that was required.