Rattling Noise When A/C Is On?

2004 DODGE DURANGO
141,000 MILES • 4.7L • 4WD • AUTOMATIC
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REALWOMAN4U2015
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  • 14 POSTS
When I turn on my AC I’m hearing rattling noise and truck was running loud while I was driving. When I turned it off, the noise went away and truck began to run normal afterwards. Not sure what’s going on.
Any idea as to what this could be?
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Jun 9, 2026 at 10:33 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
Yes, this sounds like the AC compressor is coming part internally, I would not run the AC anymore until the compressor is replaced. Here is a guide to help you change out the compressor step by step with a video to help you vacuum down and recharge the system with instructions in the images below to help you with your particular truck.

https://www.2carpros.com/articles/replace-air-conditioner-compressor/

and for the vacuum down and recharge.

https://www.youtube.com/watch?v=4EqdrBVb0sY

Make sure the system is empty before replacing the compressor and read the guides completely before beginning. Check out the images (below). Please let me know what happens.
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Jun 10, 2026 at 2:44 PM
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REALWOMAN4U2015
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I took my truck to the shop to have them look into this further. The tech noted during the inspection, he found the AC compressor pulley bearing is bad and the clutch coupling was melting and smoking. The AC worked for a couple of seconds, but it quit working on him. He said the AC compressor is causing a mechanical inertia drag on the engine. They are going to replace the AC compressor.
Jun 23, 2026 at 8:52 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
Excellent find, please let me know if that fixes it.
Jun 24, 2026 at 1:32 AM
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