If your vinyl fence is dirty with spots and/or mold, you may want to try using “Mold Armor EZ House Wash” or “Wet and Forget”. Several homeowners have had success using these products to clean the vinyl. The dirt and mold should come off with a light scrubbing.
These products can be found at hardware stores like Home Depot and Menards.
DO NOT use bleach on your vinyl fences or siding. The bleach will discolor the siding and the fence will turn yellow.