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Hi Chris, I'm Brian and I'm here to help!
Do you have the model number of your Bryant furnace please?
Thanks for the blink status. I'm not sure the number you provided is the model number for your furnace. Typically the model number can be found on a data sticker on the inside of the furnace after removing the blower panel and is normally an alpha-numeric string like AAV340xnnnnx or MAV355xnnnnx Typically the heartbeat flash code is a healthy furnace at rest. The full model number will help greatly.
Awesome! Thanks. I will pull up the manual and have a look and we'll get started on the diagnosis. Beside the red led, when you set the thermostat for heat and turn it up, does the furnace do anything at all?
Ok, thanks. On your furnace a continual fast flash is reported as a "polarity reversed" alarm. This means the control thinks the hot and neutral has been reversed. In reality what it usually means is that there is a poor, loose or corroded ground connection somewhere in your furnace. You should turn the power off and carefully look over EVERY ground connection in the furnace. Especially the Green/Yellow wire the goes from the gas valve to the control board. Also check that connection at the control board. The flash code can be reset by powering down the furnace for 30 seconds or so to let the capacitors drain then restoring power.
Try that and let me know what happens.
Do you have a volt/ohm meter and knowledge of its use?
Ok thanks. This led code could also mean you have low incoming voltage or there is still a ground problem. If on the remote chance you've had recent electrical work done, there could be an issue with the incoming power circuit. If you have two furnaces that are tied together to act as one, there could be an issue with the "twinning" of the two. When all the above issues have been checked and ruled out (which unfortunately requires a meter), then the next conclusion is to condemn the furnace control board itself. I wish I had better news for you.
I will open this up to other experts to see if they may have anything to add.
Ok great! There are a bunch of us online tonight and your question was picked up a couple times so it appears no one had anything else to add so let's try some probing with your meter and see what we can find out....
The first thing we should do is turn the power off to the furnace. Now with your meter set on its lowest resistance scale, short the meter leads together and ensure that the meter reads less than a half an ohm. If it passes that test your meter and leads are good and you should put the black meter lead to a good spot on the furnace chassis near the burners (you will have to take the other panel of the furnace off if you haven't already to gain access to the burner area), now put the red probe lead inside Pin #8 on the white Molex plug on the control board. Make sure the red probe lead touches the brass connector inside the connector! Pin #8 will be the one with the Green/Yellow wire going into it. Tell me what the meter reads in ohms (or hopefully it's reading <0.5 ohms. This will check your ground connection for sure.
Ah, ok. Does it read voltage in volts directly?
Ok thanks. That's not really going to tell us what we need to know. All I can really tell you to do is what I have already. I would double and triple check all electrical connections in every spot, every spade terminal, every wire nut connection, every screw connection and every chassis ground connection.
The odd thing about this is your fan is running all the time. The reverse polarity alarm should not make the board do that. Does this still occur if you turn your thermostat off and recycle the power to the furnace to reset any alarm?
You can just turn the thermostat to off (or just down if there are no switches). Then power recycle the furnace and see if the constant flash code persists. I just want to see if it's only a call for heat that initiates the flash code or if it does it all the time regardless of anything.
Turn the power off to the furnace by the switch that should be next to it or the breaker or fuse in the main panel for the furnace. Actually just taking the blower door off will do it too as long as the blower panel safety switch works ok. Leave power off of it for at least 30 seconds, then power it back up.
Even after removing and restoring power to the furnace?
Ok thanks. I was just reading a little more about that control board. Nothing I haven't covered already. The one thing you can do is try a board self test. With the thermostat off, the unit power on, the blower panel safety switch taped over to override it, short the Test/Twinning terminal to the C terminal on the low voltage terminal strip with an alligator clip set or a small piece of wire stripped on both ends and bent to short the terminals together for 1 second. The led should flash a code then start the inducer fan and run it throughout the rest of the test. Then it will run the following in 15 second intervals: the hot surface ignitor > then the blower in heat speed > then the blower in cool speed. I doubt this will work but it's worth a shot. If it fails the test (or fails to test) I would probably say the control board has failed. I would prefer a meter to confirm some of the doubts and you may want to have a tech check it out before you go and purchase a new control board.
Yeah, even that points more toward a failed board but I agree it's probably best to have it checked by a tech since I couldn't help you come to a definitive diagnosis. Feel free to follow up, I'd be curious to know what happened. Sorry we couldn't get you heating tonight.