hey guys i was wondering if someone could give me a hand with this furnace i was tryin to troubleshoot..........so the furnace kicks in and the burners come on but as soon as the blower motor kicks in.....the burners shut off. i have changed the control board and still having the same problem. i checked all the wiring connections from the flame sensor and measured flame current which was good. i checked for broke wires too in the gas valve circuit and these wires were good. is the relay in the gas valve shot??? the led code that the furnace is giving me is a 4-5 thanks for the help
There should be lockout codes on the back of the front door.
What's the model #
Does the main fan motor run for 90secs before the inducer motor starts?
I would look at the pressure switch. If you have a dual port manometer you should measure the "w.c.
Or disconnect the wires going to the pressure switch and connect your multimeter leads on the pressure switch terminals. Set the meter to audible resistance mode. Touch your leads together and make sure you hear a beep, so you know you're in the right mode.
Start up the furnace, after the inducer starts put a jumper wire between the 2 wires you disconnected from the pressure switch. If the burners fire and stay on after the fan starts it's most likely the pressure switch opening. Your meter should constantly beep once the inducer has started, and if the beep stops while the inducer is running the pressure switch is definitely the cause.
Those Bryant high efficiencies can plug up or crack. I would analyze the flue gasses and see if there might be a crack in either of the heat exchangers.
Also take a quick look at the venting and intake pipes and termination.