A/C Idle bump up issue.

2000 XJ 4.0 4WD AT, Bought this jeep Mar 2014 with 87,000 on it now has 189,000, When I turn on the A/C the engine Idle would bump up about 150 rpm when the compressor clutch would engage & go back to base idle when the clutch would disengage, about a year ago the idle no longer bumps up when the clutch engages, I didn't think much of it for a while figuring that without it I would probably get a little better mileage, but I am now finding that it is probably necessary to keep the alternator output up when under full load (Headlights + wipers + cooling fan + max A/C etc... ) there are no regular idle issues. maybe a PCM input issue, Would appreciate any ideas !

My 97 idle falls a little when the ac comes on. I had always thought it should bump up spme when it clicked on. sorts like the extended idle switch does. At time my idle is very low with the ac on because of this.

Don't fix what ain't broken. If anything, the low pressure switch on the A/C is weak or has a poor wire connection, or the Idle Air Controller needs a good cleaning or is weak. If it doesn't actually stall, you can probably idle for several days straight with the A/C on before the battery would run down.