My blower runs fine when I pull out of the garage in the morning. 15 minutes into the drive (it's Fairbanks in the winter, so it's cold) the blower slows until it stops. The voltage isn't dropping, just the speed of the blower (down to not blowing any air). Are there wiring diagrams available? Looking for the resistor that determines the speed, or some other explanation. It's too cold to go without heat. Just an update...Since the voltage to the blower wasn't varying, I figured the blower itself was malfunctioning. I replaced the blower and now I have heat again in my car.