AC help

[blazinjake]

I've finally gotten the heater working in the 98 blazer that I bought from a lazy ass that half ass fixed his stuff... anyway a simple cleaning out of the heater core fixed it. however now that it's 110 degrees outside, the heater isn't what I want anymore.. but the heater wont go off... a few months back I noticed an annoying ass sound of something moving back and forth somewhere behind the glove box and it sounded like (and felt like) the heater was going on and off... after about a week it quit and the heater stayed on... not a problem when its 30 degrees and below... I noticed one day i took the battery cables off to fix some things in the engine and the noise started back for about a week and went away again...same deal... i figure this has to do with why I can't get the heat to go away and the AC to come on... a friend told me there might be a leak in one of the vacuum hoses dealing with the doors to turn on the heater and turn it off... however, before i get out there and work on it I figured someone would have to know what's going on with this and help me out with what I need to do before I waste alot of time in the heat...btw, I've searched or tried to.. all i can get is vacuum lines for in the engine.... I would appreciate your help!!! (so would my wife and german shepherd...)