The heater fan in your Jeep Liberty only works on setting number 4 What could be the problem Is it the switch or something simple?
This also happenned on my Liberty. It was not in the switch or in the fuse box, a part needed to be replaced by the dealership.
Addendum: That might have been the fan speed resistor block that they replaced.
Ninety-eight per cent chance that was the fan speed resistor. I bought one on eBay for $27 and replaced it in about 10 minutes. You need to drop the glove box by pushing in the holder clips. Inside you'll see a part with several wires held to the heater housing by two bolts. Remove the bolts, turn around the assembly, and there's your resistor, ready for replacment. Piece of cake.