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vors · Jan 1, 2009, 06:52 PM

Hi, I was out all day and when I came home my house was freezing and the furnace wasn't on. It's a Bryant Plus 80t according to the front panel, but the online manual shows different pictures and descriptions when I look that up. The LED status is flashing 4 short, 3 long, which doesn't match to any of the codes listed on the front cover. When I put the front cover back on (or just hold in the button that the cover depresses) the furnace will start up for 10 seconds or so, then get louder as the next component starts up, and that's when the LED status starts going. I never see any fire in the burner holes. After a few minutes running like that it shuts off again. I tried power cycling it and turning the gas off and back on, but same thing happens and now my thermostat is off too.

Appreciate any help, it's freezing in here. 2009 is off to a bad start.

KC13 · Jan 1, 2009, 06:58 PM

Double-check the LED code. Could it be 34 (3 short, 4 long)?

vors · Jan 1, 2009, 07:10 PM

Definitely 4 short 3 long. I doubted myself on it until I had checked it 5-6 times.

KC13 · Jan 1, 2009, 07:17 PM

If the circuit board is a replacement, it may give fault codes that the original board (and service label) did not. Label should have been replaced if this is the case. Is this a possibility? Compare date code on circuit board to unit serial number (first four characters indicate week and year of manufacture).

vors · Jan 1, 2009, 07:48 PM

I'll check, thanks. Quick question, though. Since I powered the furnace off and back on the thermostat has been off completely. Even if I do something to the furnace to make it work, wouldn't it not do anything without the thermostat?

KC13 · Jan 1, 2009, 07:59 PM

If you have a Bryant digital thermostat and the display is blank, it suggests that it is not being powered by the furnace. This could be connected to the fault display situation, so the first step is to determine the problem with the unit. Just a "reach": if, by chance, the board is a replacement AND the box is lying around, see if there is a service label inside... one that has a code "43"... the board should have a decal with a date code, and the serial # of the unit reveals when it was manufactured (example: 2204 indicates 22nd week of 2004). If board is newer than furnace... ya dig?

vors · Jan 1, 2009, 08:39 PM

It is a Bryant digital programmable thermostat. As far as I can tell from pictures it's a TSTATBBPRH01-B. Is there a way to power it back on manually? Or is it just always on if there is power?

How do I get the furnace's board out of the grey plastic case it's in? I have no box, or original manual. I haven't had it serviced since moving in very recently. All I know is that it was installed 12/29/2000.

KC13 · Jan 1, 2009, 08:49 PM

No need to remove board from casing to view date code. It should appear on the front near the part # of the board - might begin with "HK42FZ---". You have what is called a thermidistat, and the display will remain blank without low-voltage power from furnace. Try this: locate the square multi-pin connector near the center of the board, and push in on it a few times. Try the furnace again, see if anything changes. Some of these boards experienced circuit failure of the multi-pin receptacle.

vors · Jan 1, 2009, 09:18 PM

Sorry I see the part # (HK42FZ010) but nothing that looks like a date code. Tried the big square power connecters, too, but they were all the way in. Thanks for all the suggestions, though. I appreciate you taking the time to help.

KC13 · Jan 1, 2009, 09:35 PM

Fault code 43: Low-heat pressure, draft safeguard, or auxiliary limit switch open while high-heat pressure switch closed. The draft safeguard and/or auxiliary limit switches can produce the situation you have if one or both opened.

vors · Jan 1, 2009, 10:03 PM

Dude you're a saint for helping out so much so quickly. I found one limit switch that was clicked out, followed the wires and found the other that was clicked out and now I have heat. The filters were pretty gross so I'm guessing(hoping) that's what caused it. How soon would it trigger again if there was another problem? Thanks again!

KC13 · Jan 1, 2009, 10:28 PM

If filter replacement doesn't solve the problem, you'll find out pretty soon, within a few minutes. If the service label doesn't list fault #43 then the circuit board is very likely a replacement with enhanced diagnostics, and someone forgot to put the new sticker on. P.S. What makes you so sure I'm a dude? Is it because I sound way too smart to be a... oh, never mind, a gender war will ensue if I don't shut up now!:D

vors · Jan 1, 2009, 10:50 PM

No way! "Dude" is an exclamatory honorific unrelated to gender. It's short for "oh wise one". Male or female, you're my hero.

KC13 · Jan 2, 2009, 04:20 AM

Originally Posted by vors

No way! "Dude" is an exclamatory honorific unrelated to gender. It's short for "oh wise one". Male or female, you're my hero.

Ok, I can live with that, and the judges accept your answer. It's still your turn, spin again...

KC13 · Feb 26, 2009, 09:45 AM

It's the afterthought that counts, not the size... on a routine service check of a Bryant 352 (90t), I discovered that the unit was fitted with the wrong service and electrical diagram labels. After consulting the local product specialist, we concluded that something got out-of-sync during an assembly line changeover. The correct labels were provided by Bryant free-of-charge. You may have a similar situation with your unit if it still equipped with the original control board. Check your service label to see if the part number matches this one - 320893-101. The electrical diagram label from the 90t won't match the 80t, but the service label should.