DIAGNOSE – I HEAR A LOUD SQUEAL WHEN A/C IS TURNED ON
A loud squeal is produced when the A/C is turned on.
This symptom is usually caused by a loose or worn air conditioning compressor belt. When the A/C is activated the compressor is engaged. This places a load on the engine and the drive belt that rotates the compressor. If the belt is loose or worn the belt can slip on the compressor pulley and emit a loud squeal.
The drive belts should be inspected for proper tension and wear. A properly tensioned belt should have aproximately 1/2″ of deflection at its greatest span between pulleys. Inspect the belt for wear. Belts can become glazed on the inside drive surface which can cause them to slip, which produces the loud squeal. Some vehicles use an automatic tensioner that contains a large spring that keeps constant pressure on the belt. This system automatically tensions the belt to the proper tension. This system is often used on vehices that use a serpentine belt. This type of system uses one belt to drive many accessories.
PRECAUTIONS, TIPS, and NOTES
Use caution when working around hot or rotating engine parts.