From the wiring diagram, it looks like you would need to ground the wire to the coolant temp sensor to make the fan come on, not just pull it off. The other switch that can activate the fan is the receiver dryer temp switch - blue wire. The aux fan should come on 100 degrees coolant temp.

Both of these feed into a relay which turns the fan on. This has feeds from Fuses 2 & 10. The relay is located above the fuse box. It has Black/Red, Red, Brown/black, Black, and Blue wires. The Black wire actually powers the fan.

When you turn the AC on, you put additional load on the engine, and the condensor, which sits in front of the radiator, heats up. So yes, you would expect to see a temperature increase.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe