I had the exact same problem. Does the sound change when you use different doors? Floor, defrost etc? Did you use a Fram filter? I did, same problem your'e having. I pulled the filter 6 times, no kidding. The final time I made sure all air and blower was off and the air flow on the filter was correct. When I put it back in I went through all the doors with the blower on low and it quit. I don't know why. It quit though. Sorry about the problem.
Only pic. Bought it last month and so far pulled the grill and removed the chrome "strips", 2.5" front level, 3" rear blocks, Iboard running boards and did the fog and bright light mod.