Hvac fan only works in high speed 2004 dodge dakota

The diagram is for v6. The top wire at blower motor is voltage, the bottom wire is ground. Use a test light and check both voltage and ground. Key on--hvac on. If you have good voltage and ground with no blower action, suspect the blower motor. The blower motor is usually under the passenger side dash.

blower motor resistor...it cuts power to lower settings...easy fix usually under passenger side glovebox two screws and harness looks like a metal card with plastic bottom...

sounds like heater blower resistor

Could be the high speed relay.

get a new fan motor resister.

the high blower relay controls the high blower only
you need a new blower motor switch you control on the dash

a good place to start is at the autozone where you can purchase a haynes manual-they have detailed teardown and troubleshoot procedures or go to the library.

Sounds like tou need to replace blower motor resistor, it is located on A/C, heater case near motor. This should fix you right up. Have a good one!

the fan relay(resister) that control fan speed is probably burned out.When this occurs it will only blow at high speed because its getting 12volts directly to the fan

Sounds like a defective speed control resister.