I have a 98 Accord EX, 4cyl. with automatic transmission.
I am feeling a vibration in the steering wheel and drivers seat when the air conditioner is on, mostly when the two radiator fans come on and I notice the idle jumps up some.
There is a slight vibration, hardly noticable, when the AC is off, so I know this problem is connected with ac running.
The vibration is really noticable when the two radiator fans kick in, the idle jumps from 650 to 750 (just guessing the rpms, the guage isn't clearly marked) the vibration gets worse. Anyone have any ideas what this problem may be?

 

Watch the drive belts as this happens. Look for perhaps the AC belt being loose? Or a bearing in the AC compressor clutchallowing the pulley to wobble?

What about a fan out of balance? When its cold & not running, grab a fan & try to wobble it.Both fans should spin smooth without any ability to rock or wobble.

But just the added load of the AC makes the engine work harder, so it should be noticable. Just how much is normal is tough to say over the net.

 

Suggest adjusting the base idle speed. On earlier models, you disconnect the IACV, adjust idle speed to 700 =/- 50 rpm, then reconnect the IACV. Reset ECU by pulling BackUp fuse for 20 secs.

good luck

 

Check the front motor mount.