Sounds like the blower motor resistor is on the fritz. Replace it and it should work. I am not familiar with that model or I would tell you where to look. Usually on the passenger side of the inside of the vehicle under the glovebox area. Hope this helps.
Replace heater motor resistor.
2001 dodge ram 1500 ac and heater flow regulator switch does not work. works only on defrost. How to fix?
You need to start out by checking the a/c-heater controller and the a/c-heater doors behind the dash for proper operation..............
Probably the blower motor speed resistor is partially burned out.
Resistor on the heater blower motor has failed
You will have a bad blower resister and the part will be around $124.80 dollars.........
You most likely have a problem with your blower RESISTOR PACK or rheostat. This is what controls the high, med and low speeds on your heater. Where it is and how to change it depends on your vehicle.
The stage 1 relay has blown! it is located behind the glovebox door above the heater blower. # find it # pull it out # replace it job done:-)
The blower motor resistor is bad.
Blower fan inoperative or only works on high speed.
Dodges are good for blowing fuses. If that is not it, the fan switch might need replaced.
Low on coolant. Stuck open thermostat. Plugged heater core. Faulty temp blend door.