04 BMW X5 4.4i humming noise behind dash

[Neil1982]

I have a humming noise coming from behind the dash on the drivers side that is only on when the heater is on. It does not seem to me that it’s the blower motors but something else. Any ideas?

[ahlem]

How about leaves in your fan. Or the heater motor. How many miles on the vehicle?

[Neil1982]

146,000

[Neil1982]

You don’t hear it unless your parked with the heater on and the engine running.

[80stech]

So doesn't change pitch with blower speed? It might be the auxiliary water pump that is mounted on the driver's fender. Try turning engine off and using the rest heat function.

[ahlem]

I'd suggest getting a Harbor Freight stethoscope and zero in on the location from both sides of the firewall. Very handy to have.

[Fifty150hs]

Originally Posted by ahlem

I'd suggest getting a Harbor Freight stethoscope and zero in on the location from both sides of the firewall. Very handy to have.