How do you loosen the belt on the air conditioner?

Only older V-belts can be loosened. First loosen the lock bolt. Now, turn the tensioner bolt counter clockwise. When proper tension has been reach, re-tighten the lock bolt. On newer cars with an automatic tensioner, the tension will be correct unless the spring in the tensioner is broken. That would cause the belt to be too loose and the tensioner will need to be replaced.