I have a Lennox furnace model G23Q3/4-100-2. When the thermostat calls for heat, the igniter will light the pilot, the gas will come on and light, but the blower does not come on and the furnace will shut off after a few minutes (overheats because of no blower). I can turn the thermostat to on instead of auto and the blower will turn on and the furnace will work correctly. I replaced the thermostat and still have the same problem. The furnace is 11 years old and the control unit (Johnson controls G776RGD-14) has been replaced by a technician twice in the past. Is the control unit the problem again? Does this unit have a history of problems?
Thanks

hvac1000

It could be a fan limit controal if your unit has one. The Johnson part number you gave is for the ignition and not the fan.

Hopefully someone will be along that has a Manual for your furnace or more experience with lennox to help you locate the fan control part number.

labman

Sounds like the control board is gone again. It uses a different relay for fan on and the furnace. Maybe check your control voltage, should be 24 volt.s

sheese

I bought a lennox 8 years ago. I have had nothing but trouble with the blower and the control board. When the blower has trouble it shorts the board and $350 up the flue. Never buy a lennox. I am getting rid of the lennox and get another furance.

sheese

I bought a lennox 8 years ago. I have had nothing but trouble with the blower and the control board. When the blower has trouble it shorts the board and $350 up the flue. Never buy a lennox. I am getting rid of the lennox and get another furance.

wmproop

more than a bunch of people have big regrets about buying a lennox,,around my area you can`t find local parts ,they have to be ordered,,,with a long wait