It is next to the blower motor underneath / behind the glove box. It is held on by two screws and has a 4 or 5 wire electrical connector plugged into it. you will find it in the air box, inexpensive to replace. I jury rigged mine for a month by driving a screw through the area that had the break in the printed circuit resister. High speed bypasses the resistor pack so at least that is always available in the meantime.
replace the blower motor switch
Under the dash, on the passenger side.
The Blower resistor should be tested which is located near the blower motor, the resistor is probably faulty.
The blower motor resistor pack is bad.
blower motor resistor is burned out
sounds like the blower motor resistor is out on the lower speeds.
Your truck has both. the resistor is between the switch & blower.thje resistor controls the blower speed
For the 1989 Dodge Ram, the heater blower motor resistor can be found on the passenger's side, on the bottom of the heater box. It is beside the blower motor.
I had the exact same problem with a 1999 Dodge Stratus. I replaced the blower motor resistor twice only to find out that the blower motor itself was the problem. I know others with the same type of car, i.e. Dodge Stratus that had this problem. It turns out that Chrysler must have gotten a bad batch of blower motors form some supplier. I went to the junk yard and got another used blower motor and put that in with another resistor (the second one blew out again) and it worked fine!
Blower motor is under the dash on the passenger side.
The resistor block or blower motor resistor is used to control the speed of the blower motor. That is how you get the lower speeds on your air conditioning or heater. The higher the resistance the lower the speed of the motor.
The resistor is under the passenger dash just left of the blower motor