I drive a Renault Clio 3 built in 2011. When the motor is off, but the key is turned one notch clockwise (i.e, power is supplied to things like ventilation, but not to the ignition), there is a beeping noise in the engine compartment. I took a video of it, you can find it here:
It seems to be the loudest at the upper-left corner of the motor block. The volume is so that if the engine compartment and all doors are closed (but the car and the ventilation are off), it is barely audible in the car.
When I switch the power off (i.e., turn the key into the "completely off" position), there are three clicking noises interrupting the beep, which then stops. You can hear that here (video is not useful since I had to put my phone done in the engine compartment):
Can anybody identify what is making this noise? Is this a reason for concern? Thanks for any help!