My AC works great & sometimes it doesn't work at all, smoke thru vent once? on 2004 Cadillac DeVille DTS

Smoke & burned rubber smell occured once but AC worked great the next day without the smoke or burnt smell, & car won't start now. Battery says 11.1 battery ok, just makes a click, click,click sound. Please help

Asked by for the 2004 Cadillac DeVille DTS
could be a blend door issue or compressor failure,seek diag
Thank you very much, you were extremely helpful. You were a lifesaver, good to know there's people like you who are willing to help a stranger, again thank you & god bless you & your family.