To give a little background, I'm a mechanic here in AZ, I bought my 07 2500HD Hemi a little over a year ago. After buying, my transmission gave out. I had my transmission done and did a lot of other things, Water pump, Changed all plugs and coils, Decarbed, cleaned my intake, IAT, and MAP, New alternator, Grounded my TB (after a little research on here to figure out why), running K&N recharge in stock housing, and have changed out every fluid in the truck. I run mobil 1 Full synthetic high mileage (truck is at 168k)

With my A/C on at at Idle my engine surges regularly, rpm increases, my vacuum drops a little, my engine load increases, and my timing advance drops from about 12.5 to 7 degrees. Is this normal and i"m worrying over nothing or is this an issue? it seems like my engine should be able to keep a steady idle with the A/C on. These are some graphs of data relevant to my situation.

 

I would bet that the load increase, etc, coincide perfectly with the compressor cycling..... which would be perfectly normal. I think I would be tempted to check system pressures, and see if it isn't a bit low on refrigerant...... compressor really shouldn't cycle too much at idle.