Just started using A/C as it’s warming up, and noticing interesting behavior on belts / pulleys. Is this normal?

[Kegworth]

What brought my attention to it was when I’m idling and the A/C is on, i can hear a very prominent click and the idle drops, then click, and it goes back to normal. This doesn’t immediately happen when i press the A/C button, but only when the A/C is on. It looks like the pulley is seizing in these moments. The belt keeps spinning but the pulley stops.

 

[Dirtman]

You sure you're just not seeing/hearing the AC clutch engaging the pulley? The AC compressor does not run constantly when you turn the AC on, it cycles on and off engaging and disengaging as needed via a clutch mechanism on the pulley. When it engages, it not only clicks but the idle drops momentarily as the engine is under more load and then the idle raises momentarily when it disengages as the load is taken away.