on cars that run with fuel injection it would be the fuel pump, or high performance cars that use electric fuel pumps.
A bearing going bad.
Possibly worn wheel bearings can create a humming or groaning sound.
No, but a bad wheel bearing could.
The motor which blows air through the vents.
The humming sound is the fuel pump. this is normal the sound is the air compressor for the ELC (Electroinc level control) it pumps air into the rear struts the level the car out when you turn on the key.
Electric fuel pump
If it sounds like its coming from inside the car its probably the fuel pump if not its kind of hard to say.
It's most likely to be a wheel bearing if you jack ur car up an spin each wheel if you hear a rough sound it's a wheel bearing
Check transmission fluid and power steering fluid.
A humming noise on a 1999 Park Avenue is caused by bad wheel bearings. When bearings are loose or worn they will create a loud humming noise that will get louder and louder as the car accelerates.
Answer Humming noise from front endI just got my car fixed with the same problem and it was the wheel bearing and it is gone. Was it a fwd car?
MAKE CAR MAKES THE SAME NOISE AND REPLACING THE PVC VALVE FIXED THE PROBLEM