Bryant Plus 90 398AAZ Not Firing

[Ltvscout]

Went to use the furnace for the first time this fall last night. Turned on the thermostat and heard the inducer motor spin up. I walked away but then noticed 5 mins later that the furnace wasn't running. Checked to make sure the thermostat was calling for heat. Went downstairs, flipped of the power, turned it back on and the inducer motor spun up again. But, after 20-25 seconds it shut off with no pilot start. I tried this a few times, on/off with the power switch, and it finally took. It worked all of last night. This morning, no heat again. No matter what I tried I can't get it to fire anymore. The inducer motor will run for 20-25 seconds and then just shuts off.

What should I look for to troubleshoot?

Thank you for any help you can offer.

Scott

[jtrammel]

Sounds like a safety is not allowing the gas valve to open. Happens a lot and a tech should be able to resolve the issue pretty easily

[George2]

It could be something in the combustion air intake pipe (usually at the furnace) or there could be a blockage at the exhaust pipe.

Or, it could be a plugged drain line. Or..............It's time for a service call..........

[OldSchoolMech]

Sounds like a sfety is holding it out for sure ( Presure switch) I would call in a Tech. It's a shot in the Dark not seeing it.

DO NOT JUMP OUT SAFTEY DEVICES.

[Ltvscout]

Thank you, gentleman.

[54regcab]

If you system is intermittent see if you can "read the code" through the window on the front door of the furnace. Most will have an LED that blinks a code. Could be handy info for the tech to troubleshoot your system, especially if it just happens to work when the tech gets there.

[Ltvscout]

If you system is intermittent see if you can "read the code" through the window on the front door of the furnace. Most will have an LED that blinks a code. Could be handy info for the tech to troubleshoot your system, especially if it just happens to work when the tech gets there.

Unfortunately, this unit is from around 1990, before they had the newer intelligent systems that would display error codes.