Blower fan inoperative or only works on high 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.
The Blower resistor should be tested which is located near the blower motor, the resistor is probably faulty.
Most likely a failed blower resistor.
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.
blower motor resistor is burned out
RIGHT BESIDE THE BLOWER MOTOR UNDER PASSENGER SIDE OF DASH
On the Dodge Ram truck, the heater fuse for the blower is on the fuse panel on top of the battery. There is also a blower motor resistor on the blower motor. The fuse to control the heat control panel is in the fuse box in the dash.
Blower motor resistor assembly is located under dash board on passenger side.
The blower motor resistor pack is bad.
The 1998 Dodge Neon does not have a relay. It does have a blower motor resistor that could be bad.
Diagram for location of blower motor resistor can be found herehttp://autorepair.about.com/library/images/bl441a-lib.htm
Usually if the resistor is bad the heater will only run on full blast.