I've been through this and my dad recently went tthrough this and I'm 100% confident it is the ALTERNATOR. When the same noise started on my 02 Grand Caravan I had it looked at and was told it was the a/c compressor. Fortunately I still had a bit of my extended warranty left so the shop fixed it and it cost the warranty company $1200+. A little over a year later same issue and I went back to the same shop. The owner said it was the bearings in the alternator and they had several in with the same problem. I replaced the alternator and no issues. My dad had the same issue on his 05 T&C and a shop replaced the belt tensioner. He told me about it and I told him they were wrong and it's the alternator. He took it back and they put the old tensioner back on and replaced the alternator and it fixed it. The shop owner had never heard of it but he was glad to have the info. Just my ...