Q: Fan belt making noise

Hello. If your belt is making noise, there are several possible causes. First, inspect the belt tension and automatic tensioner to determine if they are putting adequate pressure on the pulleys, and not slipping. If the tension is poor, it may be because of a worn or stretched belt, or the automatic tensioner is worn-out. If the tension on the belt is good, then the noise could be a very worn belt; you can check for this by twisting the belt to inspect the grooves on the inside for cracks in the rubber, or pieces missing from the grooves on the belt. Beyond this, check for noise change with the AC on and off. If it changes, you may have a problem with the compressor, or the system is overfilled. The alternator must be checked as well; if it has a bad diode, it can cause excessive electricity amperage, and a heavy load, which will cause the belt to slip on the pulley. Most of these problems require taking your vehicle to a qualified technician to determine the source of the noise, and repair it.