Douglas, By this time you may have already found your issue but here's my $.02. First do you get heat at freeway speeds? What's the ambient temp. where you live? I ask because of my past experience.
When I bought my first SD it had a torn monovalve diaphram AND the foam connecting tube from HVAC fan to the cabin temp. sensor in the middle of the dash was mostly non-existant. This allowed me to get heat only when the car was stopped or at low speed. When I did get heat it was at full blast. As the car sped up the heat would fade but fan speed was still maxed. I fixed the monovalve insert as this is a common malady. I then got full heat almost all the time, this was in Oct./Nov. Finally pulled the glove box and center vents to get to the gooey foam tube. Replaced it with foam pipe insulation and that fixed the problem. Takes some manoeuvering through smallish openings and is messy though. Monovalve was definitely the easier job that I would do first. I would recommend gloves and also cover anything in old towels that you do not want to get black goo on if you attack the insulation tube that connects the cabin temp. sensor to the fan motor. Fred Johnson 1977 240D 1983 300SD 1991 A/R 164L 1996 Civic __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
