In theory, with the A/C turned on, an engine's RPM should increase 100-150 rpms to compensate for the extra load, correct?

On my '96 Prelude, with the A/C on the RPMS stay the same as it does at idle. According to my Apexi VAFC's digital RPM readout, I notice no change. There is no problems with the A/C system itself. Somehow, the engine is not increasing in RPM to compensate for this load.

With the extra load from the A/C being on and no RPM increase, my engine revs up and down at idle as if it were trying to not stall. Does anyone know where I should start diagnosing this problem? Is there an switch/sensor somewhere that would allow an increase in engine speed due to the A/C compressor being on? Is it a faulty idle air control valve (IACV)? What should I test? Where should I start?

Thanks to those who can help!!!