It's 3.8L with multi-zone air conditioning control: Since last 6000 plus miles (after about 54,000 miles driven), I am hearing a zingle-bell (don't how to describe it best) noise from rear right panel behind the 3rd row. I opened the panel but everything seems to be in order. The entire area behind that panel in the back is covered with climate related parts, so I really can't see anything visually. I tried to lightly hit with rubber mallet but not luck. The sound is so annoying, that we have stopped taking long trips. The van is mainly used for camping trips. I am hauling pop-camper. The noise is coming regardless of camper attachment. Please Help!