So I routinely start the coach up once a week and let it run until it reaches operating temperature. It's in the 40's here right now, so I usually run the heater blower on high.

I know that the high position only runs on high when the alternator is producing power.

My medium speeds are the same as off/low, so I know my resistor is most likely bad.

But tonight, while the blower was on high, I turned it to low to listen to the engine for a bit. When I turned it back to high, I no longer have high speed. My alternator light works, and it wasn't lit up, so I

am assuming that the alternator didn't die at the exact instant I turned the fan to high.

Where should I look first?