My AC blows hot , first I herd a loud tapping sound coming from behind the dash and it went from cold to hot air I have a 2003 GMC Sierra 1500

What is your question?

I have a 2003 GMC Sierra 1500, My AC started blowing hot air , It was working just fine blowing cold then I heard a loud tapping , like something was hitting a fan as it turns , I hear that noise every time I turn on the Ac it happens when I step on the gas with the ac first turned on , I hear tapping real loud then it stops , but this time when it stoped so did the cold air ! It also seems my serpentine belt keeps slipping off , what could be causing all this chaos under the hood , I'm living in Calif. and lately it's been 110 degrees I'm in need of my AC .Thankyou!

What makes this problem better or worse?

Shutting the ac off then turning it back on or taking my foot off the gas

How long has your 2003 GMC Sierra 1500 had this problem?

Since summer started