the blower fan resistor is located in behind the glove compartment to the left of the blower motor. you have to remove glove compartment to get at resistor.
I'm not a mechanic, but I do believe if you bypass the resister you will only have high speed on the fan. To that end, if the resister is your problem you should already have only high speed on the fan.
The blower resister could be bad, or the blower switch could be failing. Check the resister first, it is commonly mounted at the rear of the blower housing under the hood.
The blower resistor assembly is located under the hood, on the heater case to the right of the blower motor. Haynes Manual #36071
You will most likely have a bad blower resister..............
From the www.2carpros.com website: http://www.2carpros.com/forum/1998-ford-ranger-blower-motor-vt87146.html "(The blower fan resister is) located in the engine compartment inboard of the blower motor and slightly below it."
Check your fuse boxes.
it is probley not the blower switch. if your fan runs on 3,4 and 5 it is your blower motor resister.
Bad blower resistor?
under right side dash, near blower fan. has two screws & connector.
Start out by checking the a/c blower and the blower resister.......
Check the fuse and relay first. Then check the blower resister, then the blower motor itself. One of these is probably the cause of the failure.
If the fan only blows on high in the Liberty, check the blower resister. The resister circuit is the most likely cause.