One problem related to defogger heater has been reported for the 1999 Mitsubishi Galant. The most recently reported issues are listed below.
Ever since purchase of 1999 Mitsubishi Galant in 2003 the heater does not work properly. Engine temp is normal but blows out cold air. Give it the gas and it blows out hot air. Take foot off of gas and goes cold. Replaced thermostats told that it is a defective heater core that goes bad in all of Mitsubishi's.