blower stops while burners are on


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Old 01-18-13, 10:29 PM
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blower stops while burners are on

hi all. a new member to the forum looking for help, and hoping i can help others in the future.
i have an ultra sx90 gas furnace. i noticed a water puddle at under what reminds me of a weep hole at the bottom of the inducer motor housing. this leaks mostly when the furnace shuts down and would leak on a metal tray, and gravity takes it down to the floor where i first noticed it. its never done this till now. -- vaccuumed an air blew clean.
upon observing the furnace, i have noticed that the burners come on, the blower comes on after a lil, but then the blower shuts off while the burners are still on. seems to overheat, the burner shuts off and then the blower comes back on. things seem outa sync even after replacing the circuit board.
tested the start capacitor, it checked out ok.
is the inducer housing leak causing the blowers to turn off prematurely? thought this was all controlled by the new circuit board. they run on manual fine. its only the auto setting that the timings seem off.
what are your thought.
thanks in advance,
sportsmanfisher
 
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Old 01-19-13, 06:24 AM
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What auto setting are you talking about? Auto Vs ON fan setting at the thermostat? Because if you do that the fan will stay on 24/7 no matter what. What you describe kind of sounds like you are loosing a call for heat from the stat or possibly a high temp limit issue. Can you post a video of it doing this?

Can you take a picture of the leak?


PS. Your furnace is known for heat exchanger failure! Have it checked by a professional.
 
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Old 01-19-13, 08:10 AM
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The only reason water would drip out when the unit shuts off is if you have no water in the pea trap. Or I one of the hoses on the side of the furnace is not sitting in water. As for the motor, when it shuts down turn off the system and see if the motor is hot to the touch or if its wet.
 
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Old 01-19-13, 08:45 AM
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after a cold night, woke up this morining to begin the ivestigation again, and to check this website to see if i had any responses. ty much for the replies hvactech and ender.
the auto setting mentioned is for the fan only, and only on this cycle does the burner start and stop frequently as well as the fan. the burner will run for about 2.5mins, then shut off for 1.5mins. the fan will run for about 3mins and shut off for one. however the fan shuts off with the burner on, and will click on when the burner shuts off.. that the confusing part. its like its outa sync. it did this before and after the new circuit board.
if i set the thermostat to the fan always on, the burner doesn't shut off till the desired temperature setting is reached and the fan runs continuosly to distribute the heat throughout the house.
and strange, the water leaks have dissappeared for this hour of testing.
ty much.
 
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Old 01-19-13, 10:22 AM
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I'm not sure, but I think your furnace may have an ignition control board AND a fan control board. Armstrong made furnaces with 1 or 2 control boards under the SX90 series.
 
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Old 01-20-13, 06:48 PM
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i only see the one control board. unless the other one is deeply hidden.
 
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Old 01-20-13, 07:05 PM
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You may need to call a pro.
 
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Old 01-21-13, 01:49 AM
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i have, he was stumped when the new circuit board he installed didnt solve the issue. advised me to call another
i seem to think there is just one silly lil thing buggering up this fan control.
do the wall thermostats sometimes bugger up the auto fan settings? do they sometimes fail?
oh well, i'm learning so much about this furnace it is quenching my thirst for knowledge for a while
 
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Old 01-21-13, 05:25 AM
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Please post some pictures of your furnace with the doors off.
 
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Old 01-24-13, 03:15 AM
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pics

 
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Old 01-24-13, 03:22 AM
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the new technician put in an oem circuit board..., now with the setting on auto, the blower does not come on untill the high limit shuts off the burner. said it could be a wiring harness, gas valve, and inducer motor issues, which could all get very expensive. reccommended a new furnace also.
in one of the pics below , u can see the lil bit of water that has leaked behind where we added the drain tube. he said the seal in the inducer housing should be repaired, or a whole new unit installed.
for the time being am running the furnace with the blower set to always on.
 
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Old 01-24-13, 03:42 PM
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The blower is ONLY controlled by the fan control board located in the blower compartment or the thermostat fan on setting. Instead of running the blower all the time you can set your thermostat for electric heat which will call for blower at the same time it calls for heat. What make and model of thermostat do you have?
 
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Old 01-24-13, 07:09 PM
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What do you mean set the T-stat for Electric heat

This is a gas furnace , how can he set the T-stat for Electric heat, ??

I am intruding here, but I have a similar problem with my York Furnace.
 
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Old 01-24-13, 07:15 PM
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Bilhar381,

please start a thread of your own for your problem as every furnace is different. I highly doubt and know of no York furnaces with a smart valve gas valve like the OP has. However, I will let both of you know why this can be done:

Electric heat setting on the thermostat tells the blower to run with every call for heat by energizing G and W whereas on gas heat setting the thermostat only energizes W because typically the gas furnace has a control inside that tells the blower when to run.
 
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Old 01-24-13, 08:02 PM
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News to me

I have never seen a T-stat with a selector for GAs heat or Electric heat, this is news to me.

I did start a Thread of my own, no one has responded to it as yet-
 
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Old 01-24-13, 09:08 PM
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the wall thermostat is a honeywell 97-4730. i have put in new batteries, and have been suspicious about it.
 
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Old 01-24-13, 11:00 PM
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Cool

wow hvac, ur good. i set the wall thermostat to the e setting, the burner fired, the blower came on, heat rose, burner shut off, and a lil while later the blower shut off. so much better, all seems to work now like it should
i wonder if the settings changed on the board side, cause i didnt think the techs had changed the thermostat setting., although i guess they could of.

now for some gasket repair for that lil water leak.

ty hvactechfw
 
 

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