Its the fan blower resistor IMO...had this happen already. part is really cheap. Located behind glove box.
A 2002 3.7 the resistor fan
Replace the blower motor resistor.
sure
The heater motor speed resister is burned out.
Possibly
Replace heater motor resistor.
The blower motor speed resistor is burned out.
Check the blower resister
If you are missing the lower speeds but still have high speed, the resistor is bad.
If the fan only blows on high in the Liberty, check the blower resister. The resister circuit is the most likely cause.
The output voltage from the alternator is either too low or too high.
YOUR BLOWER RESISTER IS BAD
There is a resistor near the blower that is bad, known cause is high speed only.