Hi new to this forum, i have a 99 gmc suburban 5.7 vortec with a/c
I just resolved numerous issues that have been troublesome for me and many other members..... in any event here is a problem that is stumping me now......

I have a noise coming from what i think is the dash, can't hear it under the hood or under the car.......best way to describe the noise is...... I start the burb and i get this weird like bad bearing sound. like something scraping softly, you step on the gas it stays at the same level. no change. kinda weird. Alternator fine, water pump fine, thought it might be water flowing through the dash for heat..... can't figure it out for ****. I check it again tonight and still the same noise.

now this is the weird part..... after listening to where it might becoming from, i hit the defroster by mistake and the noise stops, hmmmmmm...... i shut off defroster noise back, turn the head lights on, noise stops..... shut them off noise starts...... so it seems like an electrical noise of sorts..... tested this method with alternator no vibration...... almost seems like some sort of electrical relay vibrating or something.....

any one have any solid ideas? anyone ever experience this?
thanks don