Does it have an air Recirculation Damper Motor?

Wheel is clean.

While you had the blower out did you check the motor shaft bushings for play? Did you turn on the blower switch to see if fan motor was noisy??........Well why not??? After all, you did state when the fan is on that's when you hear this noise!!! I think that's what i read.....let me see......... yep,, sure was!!

Pushrod. Thank you for your comments however there was no play in bushings and no noise in motor at any speed. It is coming from somewhere else. Do you think there are any vacuum hoses or some type of electronics that it could be coming from?

Well it's kinda like ziptie said, going to have to get under dash and try to pipoint the noise...we can only guess at the ususl suspects...good luck with it!!

No the sound remains the same. It just started 2 weeks ago for no apparent reason.

Time for someones head to lean in under the dash and pinpoint exactly where the mystery noise is coming from , or start unplugging blend door , mode control and recirc. motors , til noise goes away.

Ziptie Thank you for responding. Sounds like that's what I'll have to do. Do you have an idea where mode control plug is? Does the mode control have a relay or any other moving parts in it? Is it outside the car and on or near the firewall so I may easily unplug it? I know what the main blower motor does, but what are recirculation motors? I never heard of them before. Maybe one of those motors is my problem. Thanks

The other 'motors' I listed , are simply what most use nowadays instead of vacuum or cable controls to move the 'doors' that control air flow in the HVAC housing. Without 'vehicle specific' info the only suggestion I would have is what I mentioned before , get under there with a flashlight and have someone else work the controls while you listen and watch for what moves and when........sorry I can't be more help , always easier in person.