some times i go to drive my 95 Blazer 4wd 4dr. and steep on the gas it sounds like it sucking in lots of air and other times it fines. it seems to happen since its hot out. but it it when it wasnt hot out. and also sometime my gf tell when i go up a hill the air condition goes down but idk bout that but i do hear the air sound

 

Do you hear this same sound when you start it up in the morning and drive it? Goes away after a minute or so? If so you are hearing the fan when the clutch engages and yes they do make some noise.