This is a late follow up but... I contacted Thor industries concerning the whistling from my factory new RV's factory new grill. I explained the problem and at first they acted as though I was trying to con them. But then they took my VIN number and I guess they ran it through their computer and it showed that I was in fact the new owner of this new vehicle. When they came back on the line they were very pleasant. I confirmed my mailing address and they sent me a new grill (which was really only a thick rolled up screen). I unscrewed the old grill, unrolled the new screen then fastened the screen where the grill had been. No more irritating whistle, no more irritated customer!
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