Hi, been doing alot of reading and now it's time to just ask. I bought my wife a sweet '87 300D last May. This fall I noticed the transmission starting to upshift hard - almost like it has a shift kit installed. Wasn't that way when we bought it. Now that winter has set in (we're on the shore of Lake Erie in Pa) when we get in the car in the morning the climate control blasts full heat for about 10 minutes or so - no matter where the controls are set - and then can be manipulated like they should. We regulate temperature by selecting the low fan speed. The air seems to come out of the vents it should - although my wife says there's no heat on the floor. She drives the car alot more than I do. Lately I've noticed that the temp settings are behaving better than they did last month, and sometimes the hard shifting disappears.
Kind of thinking a vacuum problem but don't know where to start. At one point thought replacing the temp control was the way to go, then learned the hard shifting is vacuum related and tied in with the climate problem. Hoping it isn't the all day pod replacement where the dash comes out and all that. Please tell me that isn't so. Any help offered my wife would really appreciate.

It does sound like a possible vacuum leak/problem.

You need to buy a tool called a mityvac. They are available at autozone et al, not too expensive and useful for many things.

With the mityvac you can pump down a vacuum, and see if it stays. If not you can look around until you find it and test again.

Look around and follow all vacuum lines under the hood, likely one is cracked/broken/loose, cheap and easy place to start. Low or no vacuum will cause harsh shifting at light throttle.

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Gone to the dark side

- Jeff

I had same problem. White filter about 3 inches above vac pump in small line was clogged.

Here's a quick and dirty vacuum diagram.

http://www.performanceproducts4benz.com/drawings.aspx?bmid=72


Door locks are self contained, use vacuum and pressure to work, pump under rear seat.

HVAC controls have a single tap comes through firewall on upper driver's side, then connects to soleniod block on passenger side of evap/heater core box. You can remove glovebox to gain access to this block.

Two problems suggest a common fault. Get the mighty-vac and begin testing....

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles