G23 w/Intermittent Main Blower

[steve4223]

G23Q2-50-4, furnace starts, vent blower starts, ignites pilot, ignites burners but sometimes the main blower fails to run. Furnace then runs for several minutes before shutting down, then starts up again in several minutes and goes through the same process.

Presumably the furnace shuts itself down due to overheating (since the temperature called for by the thermostat is never reached) and once the overheating sensor resets, the furnace starts up again to try and satisfy the thermostat.

This is an intermittent thing, sometimes the main fan works and all is ok. I removed the electronic thermostat and replaced it with the original honeywell round style one and have the same results, intermittent main fan.

Also of note, when the furnace is not running, I've turned the main fan switch on the thermostat from "auto" to "on", sometimes this turns the main fan on, and sometimes it doesn't. (so intermittent here as well.)

Thanks for any help you can offer
Steve

[Toolpusher]

Sounds like your in need of the fan control brd.
I would set the stat switch to "on".
And when the blower comes on, leave on till the board is replaced.

This will save the furnace from over heating, and save the stress on the parts and heat exchanger.

[steve4223]

Thanks Toolpusher, logical suggestion, must be cooking the poor furnace. (which explains the "hot dust" smell the gf was getting in her bedroom which is above the mechanical room)

[pipedope]

problems with that blower brd i believe it's a 48k98 bcc3 brd.

[steve4223]

Thanks pipedope, sure sounds like that's the culprit

[steve4223]

Just a followup.

Ordered the Blower Control board as suggested. When I removed the existing board, there was a black mark on the back of the board (fried circuit, faulty board)

Installed the new board and all works as it should.

Thanks for your help!

Steve