heater controls on 2002 Dodge Grand Caravan

heater blower moter only works in the high position same with air cond. how do i fix it

Check your blower resistor, it is probably bad. I am not sure where it is located on your Caravan, may be near the blower under the hood, or it could be under the dash on the pass. side.
2 more answers
there is a resistor behind glove box that needs to be repalced. i've replaced mine twice. you'll see where it has an electrical connector. about $20.00 to $25.00 to replace
you need a new fan switch but first try to push in on fan switch while turning they work on electrical contacts and sometimes get dirty or warn