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!
It does sound like you have a vacuum leak. The most probable place for this leak is in and around the left fender well. That is where your vacuum resevoir is located. Follow the vacuum lines from the tank to the firewall and see if there is a bad hose. It may be easier to find the leak with the engine running.