You really need to get ALL of the moisture out. Assuming there is no source to replenish it. Remove the bulb amd try the hair dryer again. This time find a peice of tubing that you can insert into the housing, through the opening for the bulb, and use it to make sure you are getting the hot dry air into the housing. Give it some time, feel the front of the lens. It has to get warm to evaporate any moisture trapped in the housing. Double check your housing for cracks or leaks. Seal with silicone. Check the bulb assembly. There should be a rubber O-ring or seal that seals the bulb when you lock it in place. Good luck.I shooked it until all the water came out. It fogged up again the next morning. I don't know, it's a darn mystery to me.