Electric radiator fans

You guys have been helpful so far so here is another one...A previous owner to this car added the after market system to control the electric fans manually. It is a three position (middle off) switch. I think I may have one burned out/shorted fan because in one positon I can hear a(one) fan run but on the other switch position nothing happens. If I leave the switch in that position the battery goes dead very quickly (a few hours). Sound like a bad fan?

On my car the low speed fans are much quieter, but both run even on low. I'd visually check them with a flashlight in each switch position with the car off. Do both fans run on high? If they do it's not the fan. Leaving the SLP switch on low with the car off will kill the battery.