It sounds like it broke between one day and the next day. Maybe a blown fuse?
I had the same problem with my 97 galant. There was air in the heater core.
Low refrigerant charge? Bad compressor?
the air conditioner and heater are two separate things.(not connected) ;) it may have a fuse. or the it could just be bad.
== == The heater fan is electrically driven, so the fault will be either a loose wire connection, or the heater fan switch needs to be replaced. Have a licensed mechanic test the wiring and the switch function to find the fault and then repair it.
The heater core is blocked. The heater core works of circulation of the radiator fluid, while the A/C works off ciruclation of the freon.
You can but it will need to be a plastic or acrylic heater, inline heater, or have a heater guard over it, otherwise it may melt the acrylic. For smaller tanks small mini heaters are available that would work just fine. Check out www.bigalsonline.com they will have what you need.
the heater fan resister,it is or should be on inside or on outside heater box.
you can fart repeatedly into the seat on winter mornings-bypassing the need for a seat heater
fan speed control switch is bad. Replace it as long as the other speeds work fine.
I would check the coolant level first. When the coolant drops below a certain point,Warm coolant that makes the heater work is no longer present and all you get is cold air. If this doesn't work, I'd try a "hotter" thermostat.
Start out by checking that the blower has both power and ground and if so then next check the a/c - heater controller...........
Defective heater resistor pack.