Our Furnace doesnt seem to be working correct. We an: Air Pro BGM075128 and is Natural Gas. It will turn on when we turn up the thermostat.. but we never get any heat through the vents. There is a switch on the side that is "on" and one that is "fan". If we turn on the "fan" only cold air gets blown through. It looks like this is for cool air. So, if we leave the fan off and the "on" swith on, we get the furnace firing up, but no heat ever comes through the vents. I tested out the thermostat the best I could.. if I turn the thermostat all the way down, the furnace unit shuts off. If I crank it up, it fires up but again, we get no heat through our vents. Im not sure if the unit should feel warm or not when in use, but we don't feel any warmth coming off it at all. Thanks for your advise. Chris