Furnace fan problems!!!!

Started by matskot, November 24, 2023, 12:54:09 PM

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matskot

Hi there, 

Hoping someone may have some advice in this regard as I am stuck!!!

Our furnace runs fine with heat ON and fan to auto.  I can't for the life of me get the fan to run on its own on ON.  If I have heat to Off and turn fan to On both heat and fan come on!  Only 3 wire system
Red to Red, White to White, Green to Green, no A/C.  Thought fan relay on board was toast, replaced with new board, same issue.
Tried new stat as well with no luck. 

Any ideas are greatly appreciated!  We have a wood stove and I need to circulate air around house with fan.

samihabib

Jump R to G on thermostat ..if fan comes on ..thermostat is bad..if not ..jump R to G on board ..if fan runs then you have an issue with G wire line from thermostat to board