What controls airflow for the engine when the AC is on?

Hi,

I would like to ask, is the device responsible for the control of air during idle the same when the AC is on or off? I noticed that when my AC is on, sometimes the RPM goes down then eventually returns to normal(in my case 800rpm) but when the AC is off, it is consistently in 800rpm. When I try to rev my engine, the RPM goes down up to 100-200rpm then goes up to normal again. Would like to know if this is connected with the IACV?

Thanks!