I'm going to guess that your thermostat is digital?
If that's the case, there's a common occurrence on these forums of the thermostat being set wrong. You need to cycle through the modes of the thermostat until you reach the 'fan' mode. Then make sure it's set on Auto (Au) instead of High (Hi) or Low (Lo). Then cycle back to the furnace mode.
__________________ There's no use crying over spilt milk... unless it's on your keyboard.
Linear Mode
