Three problems related to defogger have been reported for the 1999 Ford Explorer. The most recently reported issues are listed below.
Blend door on the heat and ac broken, cannot warm up interior of vehicle to defrost windows, it just blows cold air(maybe outside air). Has not been fixed yet.
Defogger isn't working which makes all windows fog up.
Defrost on the front windshield did not work properly, fogged completely causing poor visibility. Mjs.