Just wondering if it's normal for the car to get louder for a couple of seconds then get quiet again with the A/C on at idle. Just noticed today that it gets loud, then quiet, but the revs don't change....

Seemed strange

Thanks guys

Derck

 

what i believe you are hearing is the fan kicking on and off. It does get really loud when your at idle with the ac on but after a couple seconds it turns off, all its doing is cooling down the motor so its not getting overheated since your running the ac off the engine.
Hope this helps
Matt

 

Your AC Compressor works using a cycling clutch, this means that when the clutch is magnetized, via electicity, the clutch engages. this is controlled by a temp sensor on the condenser, I believe. Anyhow this need for electricity causes a bigger load on your alternator. The ECU senses that the AC compressor is activated and it knows that a bigger demand is being placed on the alternator. So the ECU adjusts the idle to compensate for the increase in output needed. This is what you are hearing-its natural.

 

OK...most of the cars I've driven before seem to change idle RPMs with the AC clutch cycling. Just seemed weird to hear the tone get deeper, but no difference in the RPMs. Thanks for the help.

Derck