I have a 1985 300SD.The transmission shifts hard up and down.This only happens when I set the climate control to heat.Also there is no regulation of heat.It's all or nothing.
When the temp control is in the coodest position the trans. shifts fine..
Thanks
Bob

Bob -

Sounds like you need to get a MityVac and check for leaks in your AC system. If possible, obtain a manual for your year/model in order to deduce which device is leaking. (In my '82 300ds, your symptoms would point me toward a leak in the 'closed' side of the center nozzles. I'm not sure about your year, however.)

Good luck with it,
Wes

Sounds like a vacuum leak in the area of your temperature/heating control system.

Try to isolate the leak. It could be that you have more than one leak: One at the transmission or the line going to it and one at the back of the control unit in the dash.

Try listening down near the dash with the engine running, even take the asktray out. The hissing is telltale.

Keep us posted,

Haasman

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'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
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'65 911 Coupe (#302580)

Wes
Thanks for your reply.I'm not sure what you mean by center nozzles.There is a duct door that slams closed or open (I can't tell what way)when I start the car.

Thanks
Bob