What could be causing a high-pitched whine behind the dashboard in my Civic?

[OliviaOM]

My 2016 Civic has started making a faint, high-pitched whine that seems to come from behind the dashboard. It’s constant whenever the car is on, and it changes pitch slightly when I accelerate. I’ve tried turning off the AC, radio, and all the vents, but it doesn’t go away.

[Aubrey27]

That high pitched whine from behind the dash on a 2016 Civic is usually HVAC stuff, either the blower motor bearing or the blend door actuator. If turning the fan off doesn’t stop it, the blend door actuator is a common culprit.

[EllaL]

I had a similar thing last year. I pulled the cabin air filter housing to peek behind the glove box and found a stray leaf in the blower housing. I pulled it out and the noise dropped a lot, though it didn’t always go away completely.

[Jeffrey_L]

Another angle I chased was the belts and pulleys. The noise can ride through the dash if a pulley is whining as the engine revs up, even though you can’t see it from the hood. I checked the serpentine belt tensioner and idler pulley and didn’t find a sure fault, but the pitch did shift with RPM.

[HannahT]

Do you hear any click or change in pitch when you tilt the climate dial or flip between recirc and fresh air? If so, that would point to a blend door actuator.