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Phazeless · Dec 2, 2006, 07:40 AM

I have a Goodman GMP forced air furnace running on natural gas. It is about 5 - 6 years old. It recently went out. The draft inducer would come on and the igniter would glow but then it would shut down without opening the gas valve. I checked and found that the board was never sending a correct voltage to the gas valve. After checking all the safety switches and pressure switch and limit switches I bought a new B18099-13 control board and I will be installing it today.
Now the wiring diagram on the furnace is quite good. The only difference I see is in the wiring colors to the blower motor. The diagram says I should see a white neutral, a black high speed wire, a blue medium speed wire and a red low speed wire. I think the motor must be a four speed. It has a white neutral, a black, a yellow, an orange and a red. I know how the wires came off and I should be able to get it back together but I would like to know what the blower wires actually are for and should one of them go to the M2 connector.

NorthernHeat · Dec 3, 2006, 08:49 AM

Orange is not a common blower motor speed color. You may have to pull the blower motor and read what the plate on the motor says what the speeds and colors are. P.S. don't use low (R) for heat on a goodman furnace. And check the temperature rise when you are done.

NotAtech · Dec 27, 2007, 12:52 PM

I've got the same control board (it's actually a Tex Ins 41f-5 which is direct xover to Janitrol B18099-13 I'm told). In my goodman (also 5-6 yrs old), the draft inducer and blower are both running constantly whenever the AHU has power. I have found a replacement control board (White Rodgers 50T35-743) and will buy it if chances are good enough that a swap will stop the fans from running.

Is this just a blown fan relay or can there be another reason the unit wants to keep blowing?

Also, is there any installer programming or calibration required on a board swap or is it just straight replacement?