Check the tension of each belt by pushing on it at a distance halfway between the pulleys. Push firmly with your thumb and measure this deflection with a ruler. The belt should deflect 114-inch if the distance from pulley center to pulley center is between 7 and 11 inches. The belt should deflect 112:inch if the distance from pulley center to pulley center is between 12 and 16 inches. Another, more precise method of measuring and adjusting belt deflection is accomplished with special belt tension tools which are available from General Motors (J-23600-B or BT 33-95-ACBN). These tools measure the amount of force required to deflect a belt a specified distance. To adjust belt tension, loosen the pivot bolt(s) securing the belt-driven component to the engine block and the retaining nut or bolt securing the component to the slotted adjustment bracket. Use a levering device, such as a large screwdriver or pry bar, to pivot the component until the specified tension is achieved. Be careful not to damage either the component or the engine. Tighten the retaining nut or bolt securing the component to its slotted adjustment bracket snug enough to hold it. Check the belt tension again. Adjust as necessary. Tighten the component securely. If inspection reveals that a belt must be replaced, loosen the pivot bolt of the appropriate accessory (alternator, air conditioning compressor, etc.), slip the old belt off the crankshaft pulley and accessory pulley, then lift it out. Before installing the new belt, make sure it's the same width and length as the old one. Once the new belt is in place, tighten and adjust it just like you would a used belt.