Benz c180 2000 idling vabrites goes up and down

that which controls EGR main is failing.

Could be a defect in the ECU. But 1000rpm is not that high my cars normal is 1000rpm. but some older models were about 700rpm
The AC rise is normal. You may want to have a OBD II check by your garage or you can buy a unit to do this. It will scan the sensors fitted for any problems.

Its a faulty idle air control valve.You can take it off and clean it using a non-chlronated brake cleaner and a wire brush or and a scraperor you can replace it with a new one just make sure to reset the computer afterwards by disconnecting the ground cable on the battery for 30 seconds then start it.

I cant find a diagram however i can tell you how it goes. Starting at the alternator the belt goes completely around alternator (ridge side to pulley). pulley then over the water pump pulley (smooth side to the pulley), then down to the right around the tensioner pulley (smooth side to the pulley), then back to the left up and over the crank pulley (ridge side to the pulley), then to the right around the ac compressor (ridge side to the pulley), then up over the power steering pulley (ridge side to pulley) and then finally to the left over the idler pulley. have a good day.

check and see if you have a vaccum leak.check the vaccum hose that goes to the fuel pressure regulator.check the vaccum tee that comes off of the intake manifold and goes to the brake booster.hope this helps.

Possible Idle air control, simple to change on the throttle body

Do not remove the battery cable,this can blow the alternator,it is not like the old days,the car may have to relearn.

sounds like you have a vacuum leak somewhere

It could be a part called the Idle control Valve. It regulates the Idle speed and keeps it smooth. If it is choked up with carbon gum or the little motor inside it is faulty then it will not allow enough air too pass for smooth idle. When you put your air con on the engine is under more load because it has too turn the aircon pump so it will stall. Also you have a little device on aircon cars that raise the idle a little to compensate for the extra aircon load. If this is not working it could be that.

Try using a diesel additive Injector/ fuel system cleaner or 1 or 2 tanks This should ease carbon build up and clean out the injectors. I miss my Old 73' 220D Manual Transmission 420,000 mile and going strong when traded Great Car!!