I found the post below this weekend and tried it. It worked amazingly well. I can't yet vouch for the long term affects as it has been raining all day today. So far so good though. I also spent all day yesterday washing the roof and the entire exterior of the 5ver. Tough job but I'm glad I did it.
How to clean awning:
Lowes: One gallon pump sprayer of Tilex mold and mildew cleaner
Extend awning completely.
Spray 2-3 beginning at the roller edge on top and underside of awning, roll up to where you have sprayed
Continue to spray next 3 feet or so, roll up that much more
Finish spraying roll up awning completely
Wait 20 to 30 min.
Unroll, brush lightly on underside
Rinse thoroughly.