Hiya
Been having the same problem with my 80E for over 5years now.
Heater matrix was replaced (apparently! - if you can call garage comment of it being full of c&** and then his bodge put back together of dash replacing it!) and it worked fine for about a year or so, now only blows cold, regardless of heat setting. I've since had endless coolant and other hoses replaced, coolant system flushed & bled, radiators switches/temp sender switches/water pump housing thermo replaced - all to no avail!
Awaiting the warm weather now as my next step is to remove bleed hose and the one next to it (which go in and out of matrix) whilst the car is cold, and to force water under pressure through it to see if it will clear any blockage. Failing that, I'm looking at getting a new matrix myself and having that fitted by my trusted garage, which means at least a week without my car!
Meantime, it's a case of continued elbow grease to remove the frost from both inside and outside of the car, and a hot water bottle on the way to work during the cold weather - I kid you not!
