Quote:
Originally Posted by w0hva
The furnace works fine when the camper is connected to shore power, in fact starting my generator while the furnace is acting up resolves the problem. That's why I was wondering about the voltage minimum.
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I suspect the sail switch is the culprit of your issues. It doesn't take a lot of voltage (about 12 vdc) or amperage to operate the control board, open the gas valve, and ignite the gas. What does take a lot of power is the blower motor.
The furnace blower motor not only blows the air from the heat exchanger into the camper but it is also the exhaust fan for the burner. The blower motor is what operates the safety device called a sail switch. If the fan doesn't blow enough air to operate the sail switch the furnace sees that as a CO danger and will not allow the furnace to operate. Saying the furnace works when on shore power indicates that the furnace needs the extra voltage that the converter is supplying to operate the sail switch.
The sail switch could be obstructed (dirt, lint, pet hair) opr it could be bent creating friction. The only way to diagnose and repair is to remove the furnace if there's no outside access.