Anybody ever experience this? I am at a stop and when the A/C cycles and the fan kicks on, my idle drops down and I get a rythmic vibration, mostly in the steering wheel. I've heard this might be helped by cleaning the throttle body, but don't know this is accomplished. Any ideas/tutorials/procedures?

 

your idle will drop normally under that crcumstance, but if it is an obviously much rougher idle, you might want to check your idle boost control if you have one. 98+ accords do

 

Yea it is normal for the idle to drop a little bit when the a/c 'first' kicks on, obviously cuz of both the extra load from the compressor and also both fans running takes extra electricity, which causes the alternator to bump up the power a bit (which makes it a bigger magnet, making it harder to turn). However, there is an idle boost solenoid that actually raises the idle speed just a bit every time the a/c compressor kicks on to compensate for the extra loads, and it "should" go back to where it was idling before the compressor kicked on. Where you have the idle at initially will also have a large effect on how rough it idles with the a/c on, 4 cylinders especially since they don't make as much power, even more so at low rpms. A little extra load makes a big difference on how it idles, especially if the motor isn't in the greatest condition. If your idle isn't coming back up to where it usually idles (like the idle drops 100 rpm's or something when it kicks on), then there is most likely a problem with the idle boost.

On mine I had to fiddle with the idle speed a bit to get it just at the right speed so that it idled at regular speed with the a/c off, and also idled smooth with the a/c on, and I got it just right at about 800 rpm. All I feel when my a/c kicks on it a very slight shudder only for about a second (the a/c boost solenoid takes a second or so to react), then it goes right back up and idles just as smooth as it does with the a/c off. With the a/c on or off I can baraly even feel the thing idle.... nice and smooth. Motor mounts also make a HUGE difference on how rough it idles (idle vibrations), if they're worn or broken it'll idle hard too.