There are two heating elements in the front heater. I doubt they both would fail at the same time unless it was a heater control board or heater relay board going bad. Check to see if one side of the heater seems to be warming up. If so it could be the thermistor which is a cheap and easy fix. If you know how to use electronic testing equipment, you can test the thermistors by squeezing it between your fingers and testing the resistance. Your reading should change fairly rapidly. If it only slightly changes or not at all, the thermistor is bad.