i had similar problem with my xtrail, rough/low idling when the aircon is on. I guess your problem is the opposite that the idle is too low when the aircon is off. but both problem is caused by the AAC. The AAC controls the airinflow to the engine that controls the idling when the aircon is on/off. Unlike the carburator type, the efi engines' idling is controlled/maintained at the same level whether the aircon is on or off.

Mine was fixed with the cleaning of the AAC since its just 3 yrs old. Yours needed to be replaced.

But maybe cleaning can fix your problem. But if ever you choose to replace it, dont go for surplas sir, baka in a month or too, labas na naman problem mo. If you plan to keep your sentra for a long time, replace it with the new one. however, my old mits montero had the same problem also, rough idling when the aircon is off, i forgot the name of the part for mitsu but same as the aac of nissan. got a surplas replacement from banawe since i was about to sell it anyway, fixed it and sold it.

or if the change in idling doesnt annoy you, you just increase the idling so when the aircon is off, your engine will not stall.

just my 2 cents...