The interior fan for the ac/heat

my malibu had the same problem, I replaced the "borad", it is a cheap part, a simple plug in part. I cant remember if this style is on the ranger. hope this helps, best of luck

Yes, it sounds like the resistor block which controls the fan speeds is shot, typically when this burns up, you see only one speed -- full high, because there is no resistance to the current going to the motor. More resistance = lower speed.

Thanks, I had a brain fart. forgot the name of the part. I also miss spelled "board".... argh!!!