So when I turn my engine off and had the AC running there is a squeaking noise as something is spinning down. No noise when the AC is not on. Is this more likely a bearing/serpentine issue or an AC compressor issue?

2013 coupe with 98k miles in case that is pertinent.

thanks...

 

Radiator/ AC Condenser fan(s). They are the only two things that would "spin down" once you shut the car off. If it was a belt/bearing issue you would only hear it while the engine was running/ AC engaged.

You can try spinning each fan (there are 2) by hand and see how smooth they turn or if there is any resistance/rumbling. However, try this ONLY when the engine is cold or if you disconnect the battery. Even with the engine turned off the fans can still come on...

FWIW, I had to replace mine about 2 years ago ('08, ≈101K miles) thanks to beach sand...

 

Thanks for the advice. I will try spinning those fans this weekend.

 

Check belt tensioner