Guardian furnace won't cycle

[bbittrick]

I have an 80,000 BTU gas furnace that was damaged by an open neutral several days ago. The circuit board and transformer have been replaced. The furnace will cycle once until the house reaches the set thermostat temp and the burner shuts off but the blower does not shut off. The burner will not reignite the next time heat it called for. I can keep the house warm by manually turning off and on the power to the furnace but cannot find the reason for the failure to shut down the blower or reignite the burner. The high limit switch shows no resistance when the burner is shut down. After replacing the circuit board and clearing the initial ground fault code there have been no other new error codes.

[paul52446m]

Guardian furnace won't cycle

I have an 80,000 BTU gas furnace that was damaged by an open neutral several days ago. The circuit board and transformer have been replaced. The furnace will cycle once until the house reaches the set thermostat temp and the burner shuts off but the blower does not shut off. The burner will not reignite the next time heat it called for. I can keep the house warm by manually turning off and on the power to the furnace but cannot find the reason for the failure to shut down the blower or reignite the burner. The high limit switch shows no resistance when the burner is shut down. After replacing the circuit board and clearing the initial ground fault code there have been no other new error codes.

Does the fan run from the electronic board or is the a fan switch. It sounds like the limit switch is sticking. You say you have no resistance when you checked the limit switch, how do you check it? You would have to take the wires off the switch so you are checking across the switch. If the fan runs from the board and the limit switch is open then the blower will keep going.
Paul

[bbittrick]

I waited for burner shutdown, pulled the wires off the limit switch and tested across the limit switch with an ohmeter. There was no resistance

[paul52446m]

I waited for burner shutdown, pulled the wires off the limit switch and tested across the limit switch with an ohmeter. There was no resistance

I asked if the fan runs off the board? If it does then the board is not working right or the wired something wrong. Call the back. Paul