[ohwreg]

I just bought a 2016 i30 GD SE NAV. It comes with the gen1.x Kia/Hyundai EU multimedia (see attachment).
There is a constant fan/hum noise that comes out of the head unit (not speakers). I thought it might be its internal fan or the engine cooling system but it is there even if I unlock the car without putting the ignition on after a full night of being parked.

Any ideas what might be going on or how to test for different causes? I am afraid it might be unnecessarily draining the battery.
Thanks

EDIT:
No noise can be heard beneath the bonnet so it is 100% in the cabin. It is loudest directly at the head unit's display. It is much less audible from the vents on either side of the HU.

[sundiz]

You probably should look at the fuse box and take the headunits fuse out. Just make sure you have the activation code for the radio, if it needs one. If that makes the sound go away. If it does, you can measure the draining current with a multimeter from the fuse contacts.

[ohwreg]

This is a very good idea! Thanks.
Do you know if these units have a code and also which fuse is specifically for the HU?

[Dazzler]

Hi there,  If it is 2016, shouldn't it still have some warranty?

[ohwreg]

Yeah, it does - until January 2021. I might ask them to check it out but was hoping for either a normal known behaviour or an easy fix since I don't want to bother with them if it goes down a rabbit hole.

[sundiz]

Better to let dealer check it if you still have warranty.

As there is no sound clip from the noise, I was just wondering if the noise you hear could be from the coils. I do not know the english term for it, but some times bad coils can cause this noise in electronics. Coil whine, coil noise? Maybe some native english speaker know the real term for that. Could be mixed up as a fan noise.

Unfortunately I do not know if your unit requires activation code after power out. I've only worked with radios that do not need it.

[Shambles]

You've not left a small CD in the drive...?

[ohwreg]

No.
I decided to unlock the car and enter asap through the passenger door. Then I was able to hear the noise spin up after a split second. My guess now is that the multimedia turns on immediately after the car is unlocked in order to be seamlessly responsive if the ON button is pressed or the engine is ignited. In essence it boots up but keeps the screen and speakers off waiting for ignition or the ON button being pressed.

[ohwreg]

My guess was correct. If you unlock the car and then immediately turn on the multimedia, you will be staring the Hyundai logo for a few seconds. If you wait a bit before turning it on (after the fan starts spinning), then the unit is immediately responsive upon turning it on. So it seems it starts booting up as soon as the doors are unlocked and it takes a second or two for the fan to need kicking in.

Now, it is a different question whether the noise is at a normal level or the unit needs internal cleaning and a new thermal paste. I'll ask the dealership at the next health check-up.