I have a 2008 Toyota Sienna CE with 110,000 miles, and just started to hear a rattling noise when the a/c cycles on. When checking to see what it is. I figured that it wasn’t the ac unit. Got closer to the belt tensioner and see it moving a little excessively. Might that be the problem that I am having, is the belt tensioner or a worn out belt. Or another problem. And where can I find a how to page if it is the tensioner. Thanks, Parker.
A – Look at the tensioner when the A/C is on and the engine is running, there should bot be a lot of movement in the tensioner. Most serpentine belt tensioners have a wear indicator molded into them. There are lines on the spring and un sprung part of the tensioner that indicate when the belt has stretched and needs to be replaced. In your case, based on your mileage, it would be a good idea to replace the belt, and while you have it apart, the tensioner if it is easy to replace.
