Bluescreen

My 2004 ES330 with ML sound/nav (in case that's relevant) has a clicking/rattling noise when the air conditioner is running.

It appears to be coming from behind and slightly to the right of the climate control panel. The noise sounds like a slow moving fan where one of the blades is hitting something intermittently, or a relay is chattering. It's not loud nor consistent, starts and stops intermittently every few seconds, but doesn't go away unless I shut down the air - if I turn off the air, the noise stops. The air appears to work normally otherwise, and all the controls do what they're supposed to. Switching from top vents to lower vents to both doesn't change the noise.

Any ideas what the cause might be?

Thanks.

SW17LS

Need a new blower motor. My old 03 ES required the same repair.

Bluescreen

It's possible. Another possibility I've been reading about is that one of the servos/actuators that control one of the flaps that mix the air or direct it from upper to lower vents has gone bad.

An additional clue is that increasing blower speed increases neither the volume nor the frequency of the clicking, which makes me think it might not be the blower.

Neither possibility is heartwarming, to say the least. I'm going to play with it tomorrow in the driveway, see if changing things on the controls changes or temporarily eliminates the noise.

SW17LS

I can't remember whether mine increased with blower speed or not.

The he blower motor wasn't a huge repair.