heater/ blower noise, random intermittent 1997+

So I did some searching, but couldn't come up with anything that seemed similar to my problem. Sometimes when my blower is running, it makes a growling sound in the vents. If I change the speed, the sound doesn't really change and the fan seems to operate just fine. I get really good air pressure on the 3 and 4 settings, So I am skeptical that it is the fan motor itself. The noise goes away when I turn it off all together. The noise is completely random. Some times I can make it stop by turning the system on and off a few times, but not always. Everything seems to be working correctly except for my ac which was evacuated, and I dont use at the moment. Im hoping someone can point me in the right direction, so i dont have to tear apart my dash and pray that it makes the noise while im doing it.
THanks in advance
Lightfoot

Its a 99 2dr 4.0 ax-15 BTW

You could measure the current draw growling vs. non-growling to determine if the motor is going out.

The blower motor itself is the likely source.

Unless you are missing any small mammals from your neighborhood.