Alrighty, its been chilly the past few mornings, so been runnin the heat. Anyway, Ive noticed that of the 4 fan positions, the third one up (closest to HI), doesnt flow any air. It like shuts off the fan, Lo, BARELY moves any air, one up from it moves an ok amount, next one up nothing, and then HI is beasting air everywhere. Does this sound like a fan, a switch, or the little relay on the heater/AC box? How can I go about diagnosing which part? Money is a little tight, so I dont want to replace the fan when its fine.