When I have my air conditioner on any setting that's half power or less, the thing runs great. If I put the power/speed slider on "AUTO" (if set to a cold setting) OR to anything over half to full power, I hear what sounds like another motor or fan turn on. Also the entire car seems to vibrate a bit. The a/c still comes out cold and all, but is this a normal situation for this model? Is there something that I should have a mechanic look at?<p>I haven't had my 1988 v70 very long so I'd like to see if this is normal or not.