Help me diagnose a noise on my BMW

[wavinwayne]

Since I got my 2016 BMW 535d in September 2023, I've noticed something strange. When I'm running the AC, everything is fine, no strange noises. When I turn off the AC and leave just the fan blowing, there is a whining noise that sounds similar to a power steering pump when it's low on fluid, but not as loud. The noise will increase/decrease along with RPMs, and will be worse when turning the wheel at slow speeds. The noise goes completely away after a few minutes with the AC off, and will go away immediately if I turn the fan completely off. Car runs fine, no CEL, and has 80k miles. Any ideas what this is?

 

[BMWTurboDzl]

Since I got my 2016 BMW 535d in September 2023, I've noticed something strange. When I'm running the AC, everything is fine, no strange noises. When I turn off the AC and leave just the fan blowing, there is a whining noise that sounds similar to a power steering pump when it's low on fluid, but not as loud. The noise will increase/decrease along with RPMs, and will be worse when turning the wheel at slow speeds. The noise goes completely away after a few minutes with the AC off, and will go away immediately if I turn the fan completely off. Any ideas what this is?

Is this a sound from inside the cabin or the engine bay? Perhaps it's the alternator if you hear it in the engine bay. Perhaps a video?

 

[Oillover]

My vote goes to the electric water pump.

 

[drtyler]

My vote goes to the electric water pump.

Are you certain his car has an electric water pump?

 

[Oillover]

Are you certain his car has an electric water pump?

Some of them have an electric aux water pump for the HVAC system.

 

[wavinwayne]

Are you certain his car has an electric water pump?

I believe it has electric water pump and electric power steering.

 

[wavinwayne]

Some of them have an electric aux water pump for the HVAC system.

Would that pump turn off when I turn the blower fan off? Because the noise stops immediately if I turn the fan off.

 

[wavinwayne]

Is this a sound from inside the cabin or the engine bay? Perhaps it's the alternator if you hear it in the engine bay. Perhaps a video?

It sounds like it's from the engine bay. I'll see about making a video.

 

[Oillover]

Would that pump turn off when I turn the blower fan off? Because the noise stops immediately if I turn the fan off.

Possibly.
I mean, there's really no reason to have the pump continue running if there's no air being forced thru the HVAC system (due to the fan being turned off).