In Reply to: Faulty heater control valve? posted by David Vukovich on September 27, 2001 at 23:28:59:
It's not to hard to change the HCV. Bentley's has a good description. Basic tools are fine, top of engine compartment, a little tight so be patient. Be sure to remove/replace the HCV and aux pump as a unit. Note that you don't have to drain cooling system as they suggest. Have several (4 i think) wine corks and just plug the lines as you undo them.
I purchased a used HCV for $70, a new one was like $135 or something. Unlike the E28 unit, you cannot rebuild it.