Buzzing noise under dash when Ebreak is released?

I recently purchased a 2003 1.7L 5 speed Honda Civic. It is in amazing condition and I only have one issue that I haven't been able to diagnose. When I first start it up it doesn't make any noise but as soon as I lower the Ebreak a buzzing type noise starts under the dash, sometimes it will keep going on and on but sometimes if the heater is on it will stop after a while, and only a few times has it not made the noise at all. Any ideas or possibilities would be greatly appreciated!

Added (1). Buzzing type noise under dash when PARKING BREAK is release

1st of all, that vehicle has a parking brake and not an "e" brake ( you would not use the parking brake in an emergency, right? )… 2nd - w/o seeing the vehicle, it's not possible to know what the noise is… Could be a loose part of the dash, something vibrating or?

Car is old. Hit the dashboard with your hand when it is buzzing. Could be a bad blower motor.

I always check the exhaust shields first when a customer hers rattling noises.