In just the past couple day my heat wasn't heating the house. I opened the door and there is a red light flashing 3 times and the ignitor lights but only cold air comes out. The paper on the front of the furnace says that 3 flashed means the polarity is twinned. (or something like that) what do I need to do?

I'm having the same problem... if I find something out I will message you with the solution... Good Luck.