Most modern Andersen windows are solid vinyl. although the older ones were most typically vinyl-clad. Despite claims that "vinyl is final" and never needs painting, it can get faded and dingy-looking over the years. You can successfully paint vinyl-clad Andersen windows if you prepare them correctly, as long as you realise they will no longer be maintenance-free.
Vinyl is not a difficult surface to paint. The trickiest part about painting Andersen vinyl-clad windows will be keeping paint off the glass, weather stripping and window hardware. This is a warm-weather job, because you'll need to open the windows to paint all parts of the trim. If you have removable windows, taking out the sash for painting will make it easier. There typically isn't any hardware on exterior windows, but you'll have to remove screens. If bugs are a problem, tape some plastic sheeting to the inside of the window to seal them while you work.
Clean the vinyl with detergent and a scrub sponge, and sand it lightly. Combine the cleaning and sanding steps into one by using wet-dry sandpaper or a flexible sanding sponge to scrub the windows with detergent, then rinse them and let them dry.
Because painting vinyl-clad windows is labor-intensive work, don't compromise the quality of the job by using cheap paint. Your best bet for high-quality materials is a dedicated paint store, where professional painters shop, instead of a home improvement store.
Choose a high-quality, 100-percent acrylic (water-based) paint in any sheen you prefer. Satin finish is a nice compromise between binding gloss and a flat, harder-to-clean surface. The Paint Quality Institute does not deem priming necessary. If you live in a harsh climate and opt for priming, however, use a water-based bonding primer. Whether you prime or not, administer two coats of acrylic paint for the best look and maximum durability.
Vinyl gets hot in the sun, and as a general rule, you shouldn't paint vinyl siding more than a shade darker than the existing color, because it can warp. Because windows are a thicker material, the color doesn't matter so much; but because you're probably painting over white, bear in mind that painting a dark color could require more than two coats of paint.
If you want to match Andersen vinyl window colors, contact your local Andersen dealer. They don't provide color formulas, but will give you color swatches you can take to a paint store for custom matching.