Erratic engine revs with AC on?

Hey you'll. I just picked up my first taco EVER! Its also my first truck ever; I'm lovin' it. So here is the deal: The truck idles just fine and drives just fine when the AC isn't on. But when I turn it on, I notice at idle and while I'm driving that the engine will rev up about 500 RPM for a few seconds, then go back down. And this happens the entire time the AC is on, as soon as I turn it off, the erratic revving stops. Whats the deal? And my AC stays cold, it doesn't fluctuate in temp, its not like the condensor keeps cutting on then off...I have a 2k8 Tacoma V6 TRD Sport DC/SB 30k miles

If this is a double post my B, I did a search and couldn't find anything relating to the topic. Thanks in advance

 

that sounds a lil extreme, i would have that sucka checked out

 

According to my scangauge.... without A/C on... Just sitting at a light or sitting in a drive-thru, my truck fluctuates between 500-670ish RPM's. It'll rev up to 670ish for about 30 seconds. Drop down to 500ish for 30 seconds. It'll keep doing that while I'm sitting there.

Without the exhaust, I couldn't hear it and it was a non-issue (out of sight out of mind). And with the scangauge, I can actually see the numbers.

I'm pretty sure it's normal and just the way these trucks are. This could also be another reason for the Automatic lurch also.

 

Hmm after looking at it closer it is more like 250 RPMs it jumps up for about 20 seconds or so, then it drops. But its not just at idle, its while driving too; is that normal too? Thanks again

 

Sweet. Thanks for the help