Quote Originally Posted by FlaAveo5 View Post
I read that hissing INSIDE a car is usually a hole in a vacuum line someplace in the system. I did replace my inside cabin filter about a month ago, and this started a little later. I got a Fram filter with Fabreeze and carbon in the filter, instead of just the plain folded paper one. Could I have pinched a vacuum hose or punctured one?
The hissing is probably a vacuum leak and it may be affecting your A/C in the cabin. Try to find out where the hissing is coming from. It may be unrelated to your changing the filter and mere coincidence that the leak started at that time. The car is old enough to have a deteriorated vacuum line, or something that is causing a vacuum leak.

Either that or you have a snake in there... <LOL>