So occasionally at idle I've had a subtle belt chirp. Belt and pulleys still in good shape so nbd...then I got a little over ambitious off road. After getting unstuck my belt would squeal when the ac compressor kicked on. I revved her up, squeal went away but now a few days later a have a chirp when ac compressor kicks on and the tach drops to 500 or so. Even if the engine is spinning 3k the tach will drop to 500ish. Ac off no issue. Haven't checked alternator connections yet or voltage to see if charging stops.

 

the tach is driven by the alternator on these