RPMs drop down when Climate set on AUTO.

[FarFetched]

Whenever I set CLIMATE on AUTO engine RPMs drop down. I know RPM should go up when A/C is on. Also, whae everything is on, RPMs barely go up. When I turn steer wheel RPMs jump up pretty good. I looked in FMS and ALLDATA, couldn't find helpful info!Should the two fans (in front of condenser) come on wjen A/C cycles?On Jeeps everytime A/C compressor cycles, auxilary fan comes on!Trying to figure out this little problemThanks!

[maxnix]

Condenser fans are pressure and temperature triggered, I believe. AC compressor is continuously variable, so always runing with AC on. Doubt if it is hot enough in Seattle to get much action, yet.

[Q45tech]

How you set the pivot point of IAC.............the manual air bypass [the screw on IAC]..........the ecu tries to maintain rpm by adding air via IAC and changing electronic formula for ignition advance [mechanical base advance 15BTDC + what ever ecu adds/subtracts] ...........notice ecu adds 5 degrees from neutral to putting in drive.

AFTER totally cleaning TB, intake and plenum and IAC passages, the IAC duty cyle should be ~~10% in neutral [no AC no light load] with AC on the duty cyle should go to ~~25% when in gear 35%. Do a Power balance make sure all rpms drops are with 12 rpms of each other [dirty injector/ different compression per cylinder are faults]

As the engine ages the compression gets lower from ring wear and the stretched chains change the idle from retarding cams vs crank.......resetting manual CAS advance fixes electronic timing but not the relationship between cams and crank.

My 286k Q requires some fine tuning of IAC bypass to find the sweet spot and this varies with ambient temperature even with perfectly clean TB.

The current use of 10w40 has helped stablize the idle cylinder pressure variations..........now that we are seeing 80F.

[FarFetched]

Thanks for great insight!I did compress chk and vacuum check on engine. I haven done power bllance test yet. Compressinon within specs ~170-180 PSI Vaxcuum 18.5 steady as rock!Actually what happens is after a good drive (2-3 hours of ddrive) I stop engine, then restat (up to 30min after) and it starts to stumble in D or R and then stumbling slowly goes away! If I race the engine a bit "stumbling" goes away. It might comback later. I think I set IACV to 3 turns. I watch tach when it happens and notice when "stumble" occures RPMs don't come back to normal. Example, it idles at ~550 in D and when "stumble" occures it drops to (and below) 500 and stays there!All that doesn't affect performance at all. Spark plugs, KS, MAF are NEW. Cleaned TB, IACV as much as I could. It is just annoying! Thanks!