I have a Sunnybrook 5th wheel and the furnace just died. Does not come on. 6mo ago replaced the AC control board. Both AC and furnace share same thermostat. When switch is placed in furnace position there is a sound from the AC control relay board which I think is doing what its suppose to do but there is nothing from the furnace. I cannot hear the ignitor clicking from the furnace which I normally can until the burner is lit. I check the voltages around the furnace and there is a present 12V which seems to be ok. Also the limit switch on the blower motor seems to be ok. Would appreciate any info and what the fault could be as the furnace is completely dead.