GMC Jimmy Noises Pop

I Own A 2000 Gmc Jimmy With About 93,000 Miles. When I Engage 4wd And Start To Accelerate I Hear A Very Loud Popping Noise. Like Its Not...

I Have A1999 Gmc Jimmy, Starting At 45mph And Above When I Have The Air Condition On, My Car Makes A Popping Noise, Sort Of Like Pop Corn...

When I'm Drive If I Make A Hard Left Turn, A Loud Pop Comes From Under Car. It Use To Do It When I Backed Up. But Now It's On Turns