I have a 1986 300E (200,000 miles) and have had many problems on the
car. I have fixed some and others, I live with. Latest one is I
can't get any heat at my feet. It has never worked since I bought the
car 4 years ago. I don't think I have vacuum leak. All other vacuum
related systems work. The electrical signal from the pushbutton
heater control unit is good and the switchover valve is opening to
send vacuum to the servo when heat at feet is selected. There is a
metal sintered filter ( restrictor) fitted inside a short rubber hose
to which the vacuum line is connected. If I remove this filter, the
vacuum gets to the servo and the flaps open and I get heat at the
feet vent. With the filter installed, I get no heat. The servo don't
move. I think the restrictor is to allow the servo valve to open
slowly and maybe plugged. Have anyone ever heard of these restrictors
getting plugged up? Could it be that the car is not producing
sufficient vacuum or is there a small vacuum leak? Do anyone know
what a vacuum gauge should read when connected directly to the
I would really appreciate advise on this.
Thank you in advance
I've had three Benzes...a 560sel, 380sl and currently a 300e. NONE has
ever delivered heat to my footwell area the way a good ole' American
In my 300e, I have to turn off the dash vents and turn up the heater in
order to get a trickle of warm air into the footwell. If I don't turn
off the dash vents (using the little levers on the louvers), the hot
air will blast into my face...who would want that? It's neither
efficient nor comfortable. It's also intermittent -- the temp sensor
turns on the face-vents at odd times, seemingly willy-nilly.
I'm not sure if it is vaccuum related, or a bad design, but IMO heating
and ventilation is the ONE area where these cars suffer the most.
I have removed the restrictor from the line going to the footwell area
servo and now I get lots of heat there. This action is having a
strange effect on the system (sudden surges of air as engine speed
changes) but at least, I have heat at footwells
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