screeching noise from air vent

[wcnngt]

2019 rav4 hybrid with 15k miles. Random screeching noise from vent. This could happen after turning on the car, during driving, or a few second after turn off the car. Please see a recorded video link attached. Went to the dealer and changed blower motor under warranty. But the noise persisted. Does anyone have an idea? Thanks. 

 

https://share.icloud.com/photos/0-1julHGFIsStoU6928VSYLWQ

 

[Bernard Foy]

The only advice I can give is back to the dealership with the car. By changing the blower they haven’t diagnosed the problem, so ball back in their court.

[wcnngt]

3 minutes ago, Bernard Foy said:

The only advice I can give is back to the dealership with the car. By changing the blower they haven’t diagnosed the problem, so ball back in their court.

When I first brought the car there, the dealer would charge me a diagnostic fee $145 if no manufacture problem was found. So I was bit afraid of their ability to diagnose the problem. 

[Bernard Foy]

2 hours ago, wcnngt said:

When I first brought the car there, the dealer would charge me a diagnostic fee $145 if no manufacture problem was found. So I was bit afraid of their ability to diagnose the problem. 

Seems to me like a way to wriggle out of the warranty and Toyota should adhere to their own reputation as reliable car manufacturers and to a high standard of customer care and service.

[wcnngt]

I did some further testing. Exactly one minute after I turn off the car, something is being turn off and let out squeezing sound.

[IanML]

It sounds like a flap or some such in the ventilation system is moving, but needs some lubricant.

[Gerg]

As Ian says above. 

The flaps that control the air flow are hard plastic, but they have a soft foam edge that is integral to the flap.  When one (or more?) of the flaps is moved, then the screeching noise is likely the soft foam dragging against the inside of the shiny plastic HVAC unit - the movement of these flaps is entirely normal, but on your one the foam has some awful resonance.

The screeching noise after exactly one minute will be the HVAC computer, either, closing the 'recirculate' flap (perhaps to reduce the likelihood of false alarms from wind gusts?), or setting the heating flaps to some preferred default position.  Our hybrids do exactly this, just without making so much noise.

If I was trying to remedy this, then I would look to identify which flap is making the noise by experimentaion with the 'user' adjustments, and then try to wipe some graphite-powder lock lubricant onto the flap where the foam is rubbing.  Getting this into the right place will be the big challenge.  The lubricant has to be, or at least end up, dry, or else it will forever pick up airborne grit!  So any harmless, odourless dry lubricant, that doesn't degrade plastic or foam - another challenge!

I don't have this car, and I've not suffered this problem, so my suggestions are just theory from what I've seen when working underneath car dashboards - I'm happy to hear other people's opinions!

Do you live in a dry, dusty environment?  Perhaps some dust has already got past the (poorly installed?) cabin air filter and into the HVAC mechanism, making the flaps screech?