Check the condition of the accessory drive belts, looking for cracks, splits, or other signs of wear on the belt edges. Check the tension of each belt by pressing your thumb on the belt midway between the pulleys and measuring the amount of deflection.
The normal tension of the drive belts must comply with the requirements Specifications.
If you find signs of wear on the drive belts or their low tension, you should replace the belts or adjust their tension.