My 2016 Explorer makes a whine that I can hear at low speeds and when in neutral. It is rpm specific and goes away when I turn off the AC. Seems to be more predominate when engine is first started and not warmed up yet. Been hearing it for about 18 months. Seems louder now.

AC works great. I wonder if a shot of lubricant would help? What do you experts recommend.

It's probably a pulley bearing, and probably NOT the AC pulley. Having the AC on just puts more load on the whole belt system. You can listen to each pulley with a stethoscope, or take the belt off and give each pulley a spin. Typically ends up being an idler pulley.

If by some chance it is the AC compressor, it could be the bearing in the compressor, which probably can't be replaced separately.

Thanks. That makes sense.