I finally got some time today to troubleshoot why my leg heating flaps wouldn't open on my '85 300D. The MightyVac opened the flaps just fine when it was connected directly to the vacuum actuator. But when I checked out the piece of rubber that connects the plastic vacuum tubing to the actuator itself, I found that it was clogged. The strange thing is what it was clogged up with: a 3/4 inch long solid plastic or metallic dowel! I am totally flumoxed why someone would purposely clog the line, especially in such a hidden manner. Can anyone think of a legitimate reason for someone to do that?

Too bad, though, that it was not the only reason the leg flaps wouldn't open. As it turns out, the switchover valve is bad and I have to replace it. 12 volts directly from the battery wouldn't get it to switch over, and I did check that 12 volts were getting to the electrical connector when the appropriate button was punched on the control unit. The vacuum line from the switchover valve to the actuator checked out fine.

Of course when I removed the switchover valve I did drop the screw into the bowels of the center hump. Oh, well.

Dan

1985 300D 93,000 miles

On my 300D, a indy tech re-routed the vacuum hose, under the passenger side dash, and put a ball bearing in the outlet hose from the ACC servo to fix a no AC problem. It took me a couple of weekends to figure out what he did so I could get some heat.

My sense is that alot of techs jerryrig the ACC systems so they don't have to charge clients the high cost of replacing the servo or removing the dash to get at all of the vacuum actuators. I just wish they would document what they did, so that folks like me and you wouldn't have to find their handiwork the hard way.

JCD

The good news is that my new switchover valve purchased and installed this morning does the trick. I now have a fully functional ACC system! Hooray!

The bad news is that the benz dealer where I bought the valve did not have the proper size screw to replace the one I dropped when removing the bad switchover valve. So now I have to somehow find it and fish it out. This will not be fun.

Dan