I have a 1980 300SD with the upgraded Sanden compressor and Unwired tools ACCII Upgrade kit. A few weeks ago the “Auto Hi” “Lo” and “Bi Level” buttons no longer work to start the blower for heat. The defroster works and the blower/compressor both kick on, but not the other buttons. I replaced the switch block behind the buttons as those can burn out, but it’s still not working after replacement.
However, around the same time my diesel shut off valve on the back of the IP finally went out after leaking oil for some time. I had an inline filter in place to catch the oil as money was tight. My engine took about 20 seconds to finally stumble to a stop after the key was removed from the ignition. This was shortened to about 5 seconds after replacing, and yes the valve tested good. I then removed the brown vacuum line from the 3-1 rubber vacuum fitting near the fuse box and reinstalled and that shortened it to about 3 seconds. All I did was pull it out and put it back in a little further and this helped somehow. These cars are a mystery sometimes.
I know these are two different issues, but I feel like they are related. I’m pretty sure its a vacuum issue in both cases, but I have to add that I also had the steering lock and ignition switched replaced and replaced the vacuum lines on the steering lock as one was swolen, so no leak there. The diaphragms in all of the doors/fuel lid door are good. The trunk was good last time I checked while ago. So I’ve kept my vacuum system up as much as I can, but I’m just wondering if any of you have run into any one of these issues, or maybe both? Thanks in advance.