Our MKIII headlight fan systems are designed to help circulate air and eliminate any extra moisture that finds its way into the lamps. Running your headlight fan system should eliminate any moisture. If you are getting excessive amounts of moisture there may be a leak etc somewhere that needs to be sealed (with RTV silicone) or you can also try further covering the rear of the headlight housing. (be careful not to block the fan air flow however).
How to eliminate excess moisture from headlight
Written by SupportUpdated over a week ago