my blazer blows hot air. it is like the heater is on but it is not. it gets hot in the cab and dont know how to stop it. if you need more info just ask and thanks for the help. i need it fixed because it is summer and no a/c and like the heater on it is muder.

 

I had the same problem, turned out to be a vacuum leak behind the temperature control ***** in the dash. Maybe check there first.