I know this has been asked several times, but they never really work for me. I bought my car for $450 which was quite a steal. It'* middle end of winter with some cold weather still and the heat only comes out of the defrost and floor. I am getting vacuum from the engine cause i could disconnect the vacuum tube for HVAC and i got suction. So i could find it somewhere between the T and wherever the vacuum lines connect. Please help ,1990 Oldsmobile Toronado BASE

Does the engine idle change when you disconnect the vacuum line to the HVAC? If so, you may have a leak downstream at the head unit. Otherwise, your controller may be the culprit.

Idle stays the same, not a difference in rpm

Old trick is, Light up a cigarette, and blow into the vac line.....look for smoke emanating where it shouldn't...

Try looking @ the vac lines that are going / coming from cruise controll in eng. area!! Trace /follow them to the engine that is where the cruise & heat/ ac controller gets its vacumn from!! Maybe have to look/pull the battery tray due to some lines run under that!!