QuestionAlthough the year of my vehicle is an '87, I suspect the basic operation is similar to older models. My climate control seems to be stuck on providing heat all the time (regardless of settings or temperature). I checked the temperature sensor next to the sunroof switch and it seems to be functioning as the measured resistance changes as the temperature changes. I understand that the system uses vacuum to control heater air baffles, however I'm not sure how to go about checking this. Otherwise maybe a faulty climate control module (I don't have the electrical equipment or manuals to diagnose this problem as there are a number of IC's and sophisticated circuitry inside). What can I do to diagnose the faulty component? ALSO - the vacuum controlled shutoff module on top of the injection pump will not shut off the engine when I turn off the key. This leads me to further suspect a vacuum fault or leak. If I had a schematic of vacuum routing it would be a big help. I have a simple vacuum guage (similar to a Mityvac), but I'm not sure where to connect, how much vacuum I should find, etc. Help solving both problems would be greatly appreciated.
AnswerHow many miles on the car?
Where are you?
How many inches mercury vacuum is the pump generating?
You need to study the vacuum pump threads in
Engine Mechanical:
http://www.mercedesshop.com/shopforum/showthread.php?t=142400
You need to look at these threads.
Climate Control:
http://www.mercedesshop.com/shopforum/showthread.php?t=142408
Special attention:
Monovalve Problems
http://www.mercedesshop.com/shopforum/showthread.php3?p=1026761
Aux. Water Pump takes out CCU
http://www.mercedesshop.com/shopforum/showthread.php?t=140870
PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1987 Mercedes Benz 300SDL
Part: Mono Valve Repair Kit
Note: Heater Valve
Electromagnetic heater valve.
R3023-15174 Mono Valve Repair Kit Bosch IN STOCK $60.35
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=merc...
