[Mel27]

I replaced my Lennox blower control board with a Lennox control board kit 31M73 on my heating and AC.

Question:

I am left with the green ground wire (screwed into the back of the panal) which came off the old board which read 'heater/fan control common'.
There isn't anywhere left to plug this ground terminal into on the new board. And the instructions don't say anything about the ground.

I do have a terminal on the new board that says 'fan common'... but I have a wire that belongs there coming from the motor. (It said Fan common on the old board too)
Help!!
It's the last piece to the puzzle!! And I'm freezing in my house!

[labman]

Normally a green wire coming from a motor is a ground wire, grounding the motor housing to the case of the furnace and in turn to the hose electric ground. Thermostats frequently have a green wire running to the control board that caries power from the thermostat to a relay operating the fan motor. It will connect to a G terminal on the circuit board. Usually the common for everything is a blue wire connecting to a B or C terminal on the board.

Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire, common, to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. Most thermostats and furnaces have the contacts labeled R, B or C, W, Y, and G for the corresponding wire colors. It may be wired to have the A/C control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan. Digital or programmable thermostats may need the blue wire connected to them.

[Mel27]

Thanks for the reply,
I don't have a furnace, it's electric heat with the system in the attic.
And the 'fan common' wire coming from the motor is orange. (the other 3 wires from the motor are Black-high, blue-med. and red-low---which I only need the black one on the new board along with the fan common)
Would it hurt to splice the green ground to that orange fan common?

[labman]

The green ground wire should be directly connected to the ground wire of the house electrical system. Where the house wiring enters the system, its ground wire should be connected to the metal housing of the system. It would be best connect the green wire to the same point if it is long enough. Otherwise under any mounting screw that goes directly into the metal housing. This insures the housing of the motor is grounded even if the motor is mounted in vibration damping rubber mounts.