I have a 2004 5.4. There is an intermittent growling noise coming from behind glove box that only happens when the a/c is on and light to medium acceleration. I know it sounds weird but several times I have shut the a/c off and the noise stops imediately. When a/c not on to begin with, no noise. When using heater or vent on any fan speed, no noise. Only when a/c and when accelerating. Please advise.

 

I have it too. It's most noticeable between 800-1500 RPM, above 1500 and it goes away. My A/C doesn't blow as cold as it should between those RPMs and while growling.

My dad thinks the clutch bearings are going out.

 

I'll check into the a/c clutch....It seems to be coming from behind the glove box where the blower motor is located. Can't figure out why the noise only when a/c running. ????????????????