new radiator, new grey therm & fan clutch- Aux fan (original) running when/how/direction it should...I can be in the car driving, and temps stay below 200...as soon as i hit the AC button it can shoot up to 217...Then i parked it in driveway and turned the AC off and came back 10 mins later to 188...What the heck is going on here? Could Aux fan be running at diminished capacity?

 

How about electric fan reverse wired and running backwards? Mine was thanks to PO. If you hold plastic bag at grille, main fan should suck it toward grille. If you can make electric fan run in key position 2, it should also hold the bag against grille.

Or some combination of serpantine belt wrong, main fan mounted reversed, etc. But it is all about air flow.