So My heater started acting up today, I was wondering if anyone has a vacuum line schematics, so I can trace the vacum problem,or if anyone has had the same problem.

I have the heater setting on Floor, , when I reach a rpm of around 1900- 2000, it changes to defrost,, So I'm thinking more load less vaccum, (vaccum leak) but if If my rpm is higher then that 2500 3000 it does not change. Since I added 35inch tires, My hi-way rpm is about 1900-2000, the range where the heater will only stay in defrost, I'm thinking is reserve vaccum box, or a one way valve on a vaccum hose, what do you think.
Thanks

 

sounds like the "blend door" problem....search that in the box above and you'll find your answer, sorry i couldnt be more help

 

The diagram is in the attachment, good luck.