The window isn't defective, so you don't need to replace it.

When you say it's over the A/C unit, what do you mean? The register? If so, place an air deflector over the register and see if that will help.

The condensation is coming from the warm, moist air in the house contacting the cool glass surface. Redirecting the flow may help eliminate it.

Michael

The window is not NECESSARILY defective, but the glass surface is cool enough to have the warm moist air in the house condense on it. It's just like the condensation on a cold bottle of beer. Mmmmmm, there's a nice thought. Anyways, back to the question.

You need to reduce the realitive humidity in the house or warm up the surface of the glass. If you have a humidifier, turn it off. Make sure you use bathroom fans during and AFTER showers. If cooking pasta etc. you need to use a fan to vent the moisture outside. You could also temporarily attach some foam insulation the OUTSIDE of the window at the bottom ( a 2-3 strip would do). The idea is warm the glass by insulating it from the cold outside air.

This is a very common question. If the problem continues despite all of this, then you have a window unit that provides insufficient insulation. If this is a serious problem and continues for a long time, the only thing you can do is install new insulated glass. Make sure the edge is properly insulated as that's where some manufacturers use nice conducting spacers. Result condensation at the edge.

bydesignprez: what do you mean by "...some manufaturers use nice conducting spaces. Resulte condensation at the edge."

I recently installed insulated Pella windows and am getting condensation. Pella says the condensation is normal. The company that sold and installed the windows are coming to inspect them. I want to be armed with as much information as possible.

Thanks for the tips.