Honda Civic Type R FL5 - Really loud whistling noise from HVAC

Hi there,

Has any really smart person any idea as to what could be causing the following on a 2023 FL5 with 5,000 miles?

- Really loud high pitch whistle that fluctuates/chirps once the windscreen defrost mode has been running for 5 minutes of driving. Can hear this clearly over music.

- Becomes louder and more obvious as the car warms up.

- Happens at highest fan speed and hottest temperature setting.

- if you open the driver door, the whistle suddenly 'jumps' the instant the door closes shut.

- Can also hear the whistle when hot air directed forwards into cabin, particularly with two side vents closed.

- Cabin air filter has been changed. Made no difference.

- Don't think it is the motor blower, as I can't hear it coming from there when I take the glovebox off and put my ear up to it.

I am really worried the dash will have to be removed to access whatever is the source of the noise. Are there any failing components that would cause a chirping noise?