Heater problem
1985 Subaru GL 4 cyl Front Wheel Drive Manual 95000 miles

The defroster in my car does not work and it is becoming a pain in these cold winter months. The heater works fine and blows hot, but when I push any other button on the control panel, the heater turns on and nothing else. What could the problem be? Also, the temprature control works fine as well.