I've got a Duo Therm model 90030-812 C and have a recent and unusual issue.The blower comes on and the furnace fires about 5 seconds later and stays lit (you can hear it). The problem is that the blower continues to blow cold air and all the heat com...
Thanks guys. I just removed it from the RV and I see a small hole where the exchanger meets the burner box. So I'm guessing the issue was caused because blower air was flowing into and affecting the combustion air.
