I have a chevy monte carlo 1999, 3.1 liter with 105,000 miles. When driving only under acceleration the ac blows out the bottom vents instead of the dash. I a pretty sure there is a vaccum leak somewhere but have not located it. Thought maybe the intake manifold had a leak but both my oil and antifreeze show no signs of this. Fluids look great and car runs great. Any tips on were the vacuum leak could be located. Can a small hole in a covered vacuum line cause this problem? Please advise!!!