with every car i have owned, the RPM drops when the air conditioning compressor comes on. but i have not seen this with my 8. that is great by i still am puzzled. any ideas

 

The ECU compensates and bumps up the RPM to maintain a steady idle when the compressor cuts in.

 

the compressor load on the engine draws the rpm's down.

 

The increase in load on the engine is compensated by the PCM in order to maintain idle speed in 2 ways :
- fast action : instant increase in idle spark advance
- slower action : slight increase in throttle opening (remember, it's electronic).

Cheers,

Fabrice

 

i know the ECU is hard for moders to deal with but after having cars without one it is a real improvement .

 

removing the drive pulley and belt will resolve that issue, is it hot in here or is it me ...