1987 760t 62,000 klms with climate control. I have no vacum on the small white tube going to the Heater valve against the firewall on the drivers side. Without this valve closing the heat comes in all summer.

My question is where does this hose connect on the inside of the car & were does the original vacumm source start.

any help appreciated

There is a vacuum reservoir tank buried out in front of the radiator. It's been several years since I checked mine out so I can't give you detailed instructions but mine had a rubber cap that had split causing a loss of vacuum. Being an '87 you may have some split hoses also. Start at the intake which is the source and check every vacuum hose you can find. A Mity-Vac tester might be helpful in testing individual parts.

i have changed a lot of vacuum hose but will look for your suggestion

thanks