Where is the ground wire to heater blower on a dodge?

Year make model aside, most have power going to motor and grounds are through the blower motor resistor, setting speeds by using different resistors on the board, or in the case of automatic climate control, a power resistor control board, usually located in the heater box near the blower motor, google or ebay for one for your vehicle, get a picture of it in your head and look around the blower motor. They have diodes in them that fail and you will lose all speeds and other times, one or two.