Oldsmobile/Buick Repair: Olds Silhouette no heat, rear heat, oil lube

Question
I have a 2000 Olds Silhouette where the front heat will not work when I turn the blower on high. It just blows cold air.  My rear heat still works fine.  There is some heat if I leave the front blower on #1-low.  I have been told that it could be one of the drive motors that directs the hot and cold air flow and wondered how big of a job it is to fix.   I had just taken the van in for an oil, lube, and filter and then this happened the next day.  Hope there is enough info for you.

Thanks,
Scott

Answer
hi scott.yes plenty of info.and yes it is a vacum mtr some are elec but normally adjusting will work.put the heat on hot and get under dash move the temp selector from hot to cold at the same time watch the heater box and see the part that moves when you move the selector then put back on heat open or close this door all the way this should fix the prob. please take a min of your time to rate my service ty billymac