W210 E200 idle issue with new A/C pump
 

Hey my mechanic installed a new A/C pump to my dad's silly E class and the idle is rough and it occasionally stalls at the light. As I mentioned in another post I cannot operate the car without A/C pump engaged and the only way to stop the stalling is to turn off the blower entirely. The mechanic says the idle-up control is fubared and need to be replaced. It's odd because the car never suffered anything like that before.

What controls the idle with these silly 2000cc engines? I wanna see if there's a second opinion. I reckon the car will run fine with the ECU reset or some wire reconnected but I'm not so sure. Any similar experience?