BMW: heater, coolant lines, themostat

Question
 This is about a 1992 325i the second half of the year. i kniw this is noy your expetise but maybe you know? i thought i was having a thermostat problem because the temp was not regulated and the heater was not working. i flushed the system and replaced the themostat. noe the temp is right but stioll no heat. i checked the cold/heat knob right under the vent and it is working and i tried to check the temp selector on the heater knobs but not sure how to tell if that is the problem. any ideas?

Answer
Jason,
 You are right, this is not my area of expertise, but I can try to help.

 Most of these BMWs use some sort of valve that redirects coolant from entering the cabin when you have the temp set on "cool".  This valve will stick closed (at least on the older BMW's) and in the wintertime, it diverts the hot coolant back to the radiator, instead of sending it to the heater core in the dash.  I'm not sure where this valve is, or which switch controls it, but you should be able to follow the coolant lines to the firewall, and this valve should be near the firewall.

 Hope this helps some,
 Josh