If you can wipe the “foggy” off the glass than you have condensation on the glass, if you clean the windows and wipe them down and still can’t get rid of the “foggy” than you have a seal failure in the glass unit.
There are a few different easy steps to help prevent condensation
lower the indoor humidity level of the house- decreases the chance for condensation.
Raise the blinds or curtains at night- allows the air to move more freely around the house without getting trapped behind them.
Increase air flow in the affected area- turn a ceiling fan on or a stand up fan.
If you have damaged wood because of the condensation, Andersen Windows offers replacement stops and wood pieces that you can replace in a few minutes per window. I wouldn’t go about replacing the wood interior pieces until you have the condensation problem solved or you will be replacing parts again in a few years.
Depending on the vintage or year of your Andersen Windows there are a couple of different processes.
If your windows are 1988-1994 vintage than there is a repair process that a certified Andersen Service Rep can provide for you. This is no longer covered under the warranty as the warranty is 20 years on the glass unit, so there will be a cost associated with this but not as expensive as replacing the entire sash.
If you windows are of a newer vintage 1994-present, than the option is to replace the glass(sash) If the windows are under 20 years call 888-888-7020 Andersen customer service and they will walk you through the process. If the windows are no longer covered under the warranty you can purchase new window sash from our website. each sash takes about 10 minutes to replace and all you need is a tape measure and screw gun.
If you are unsure of what you need you can always contact us through our website and we can help you through the process. pictures are always helpful in determining what you have and what you need.