Howilng noise 2000 Grand Cherokee

I have a 2000 Grand Cherokee Limited and after its warmed up, I hear a howling noise coming from the front end of the car. I recently had them give the car a tune up and change the seals on the rear axel, but that did not fix the problem. The car has 120K miles. Any ideas?

Is the ‘howling’ noise audible when stopped or moving, if moving, at what speeds?

When turning or in a straight line?

When the engine is at operating temp or when cold?

We need lots of detail.

Thanks for the reply,

The noise usually shows up after the car has been going for 15-20 minutes, so the engine is warm. Once it starts I hear it only when the car is moving, regardless of the speed. The sound is not very loud, so it is drowned out by the sound of the engine when accelerating, making it more pronounced when I stop pressing the accelerator. It does not seem to make a difference if the car is heading straight or turning.

Cooling fans can make a howling noise as can worn wheel bearings.

Even a loose vacuum hose can under the right conditions. Notice any vacuum hoses off?

New info: another place howling cam emit from is a dirty throttle body (Intake).

(Mentioned in another post here today)