bryant plus 90 ignite problems
i am new to the forum and have been reading alot of the post. alot of great infom here so maybe someone will be able to help me. i have a bryant plus 90 propane furnace that is having intermitent ignition problems. it started about 3 weeks ago and has been getting slightly worse. right now it is happening about once or twice in a 24 hour period. when the igniter is glowing and ready for the gas nothing happens. no gas. it will cycle through until auto shutdown. when we reset the breaker it will reboot and will light in the first or second try. it may work fine for a day or so then do it again. i am thinking a sticky gas valve. any ideas?????????? oh yeah- no i have not taken the time to get the code. the wife or i resets it before i remember to check the led. On Bryant +90 the light-up sequence should be as follows: 1- thermostat calls for heat 2- inducer blower kicks-ON 3- contacts inside the pressure switch (P.S.) close 4- 15 seconds after P.S. contacts close, ignitor gets its juice (120V) (this is called a pre-purge period) 5- ignitor gets into a warm-up period of 17 seconds 6- at the end of warm-up period te control-board supplies 24V power to the coil of gas valve...valve port opens and burners light-up 7 - etc., etc. etc. no point continuing since your furnace is cooperating only up to the end of step-5 So...either the gas valve is mechanically stuck (or electrically dead), or the control-board is bad. And I'll add one more possible reason: gas? is the unit getting its gas? Make sure the gas valve knob is in the ON position (it has 2 positions, ON and OFF)...make sure too that the black pipe bringing gas to the furnace does not have any manual shut-off valve closed. How do we find out the problem? -- -- get yourself a cheap voltmeter (buy or borrow one) The gas valve should have two spade [quick connect] terminals. Put each one of the two voltmeter leads on each of the two gas valve terminals. Have someone by the thermostat call for heat. The sequence above will start happening in the order mentioned...when the ignitor starts glowing, glue your eyes on the display of the voltmeter...17 seconds into the glowing phase you should hear a click [coil of the valve getting energized] and the meter should read 24V. If the meter never read anything other than 0 volts, the board is bad [or the wires from the board to the valve have either gotten loose or disconnected]. If the meter showed 24V you should have heard a clicking sound...no gas from the valve into the burners with 24V on its terminals means your gas valve is bad. it did it again last night. error code 14. don't remember what it is. can't find my manual. put meter on the valve. when the igniter glowed the valve recieved 24 volts and opened. furnace is working fine at this time. i'm sure it will happen again, just not sure when. of course this time it lit the first try. was hoping it would not light so i could see if the valve was getting voltage. i have been right there when it happened before but without a meter. it sounded as if the coil was energized but the click did not sound as loud as it should be nor did i hear the gas coming in. For your Bryant+90 furnace, please supply the actual M/N of this unit (from the nameplate)...Bryant+90 is the generic family group name but not the M/N. IF the M/N of your furnace starts as follows: 340AAV... then CODE-14 means IGNITION LOCKOUT, and the following recommendations apply: What can you do to remedy this problem is: a. make sure flame-rod is fastened tight on its bracket and its tip is not touching any metal parts b. remove examine flame-rod, if tip surface is sooted, clean gently with steel wool and reinstall c. make sure the cable that goes from the control-board to the flame-rod connector is firmly connected (do a continuitiy test)...this is a white wire that starts with terminal-1 on the 11-wire connector and ends at the connector of the flame rod d- there are 2 green/yellow wires, one on the gas valve, the other on the house blower...make sure they're properly and securely fastened to sheetmetal on the unit (else the module loses its proper grounding) e- with a continuity tester make sure there is continuity between terminal SEC-2 on the board and ground (sheetmetal on the furnace), as well as between terminal COM24V on the board and ground...these tests should be made with power OFF to the furnace If I were you, I'd first try looking for soot on the rod. Most malfunctions are usually simple things to fix. (not always though) ok--- pulled and cleaned flame-rod. it did not look bad at all. but i cleaned it while it was out. continuity checks ok from flame rod to control box. also cleaned and tightend ground screw. sec-2 and com24v also check good to ground. replaced blower guard and turned power back on. on the first try the igniter glowed and the gas valve relay was energized with 24 volts. it did not light. on the second try it did. also i (my wife) found the manual and yes 14 is ignition lockout. one good thing, i found the squeak that has been driving us nuts for about a year now! These glow ignitors start shutting off just a tad after the gas should come out. If the glow is not quite strong enough, or if the ignitor is slightly out of posiiton, or if there is carbon or ? clogging the burner region where the gas comes out, the furnace will not always ignite, and can act sporadic where it may light-off one time and not another. Sometimes a new ignitor is enough to do the trick. You could test with a volt meter what the ohms are, going to the ignitor. Then find out what it should be for that same type new one. took cover plate off of the front of the burners. looked like there was some debris down inside the tube that is inline (kinda) with the igniter. i used a shopvac to clean. reassembled and is currently running. will see if it runs overnight without shutting down. Only time will tell. Keep us abreast. SO FAR SO GOOD!!!!!!! I looks like a power-vac should be a standard high-tech tool in the toolbox of any service tech worth her/his salt, huh? yes a small shopvac is worth it! the drebris was kinda like white fibers or small shavings about 1/2 long. not sure what they where but seems like they might have been the problem. almost been 24 hours and still running fine! 1/2-inch long huh? That's odd! How did they get there? Thanks for the updates there was also a dead wasp, although it was down and out of the way. i have no clue how they got there other then threw the air inlet. they kinda looked like pvc shavings but i am pretty sure they were not. they crumbled to the touch. guess i should have taken a pic. final update ( i hope! ). all is well. looks like it was just debris! thanks to all who helped!!!!!!!!!!!!!!!!!!!!!!!!!!! Same problem. Same solution (shopvac). Same result. Thanks for sharing!
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