I've been reading the heat/acc related topics. I have an '85 300TD station wagon. I live in Alaska. This fall I noticed that when it began to get cold out my heater did the same. I don't have a working tach so I can't relate rpm to heat output. However in my case it doesn't put out heat at all now. Not at idle or throttle down. I cleaned the monovalve in Sept. Didn't notice any other problems other than it was dirty (a very large bug was inside-how did that get there?) however now that I'm reading all the posts I doubt I was all that thourough at inspecting the monovalve seals. I want to buy a monovalve rebuild kit, but I also want to make sure that I've identified the problem. Did you rebuild your monovalve snibbles, and if so did that work?????