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bertafamily 10-15-2012 06:31 PM

Fan Keeps Running
 
I set the thermostat and after it reaches temp the fan either keeps running, shuts off and seconds later comes back on, or you hear it trying to draw power and then comes back on minutes later. Now granted, sometimes it will work correctly for a long period of time, however the majority of time it will at least start back up 2 times. also run time varys from a couple seconds to 45 minutes, until i flip the switch off.

Now, someone said check filters, checked and changed although they were not that dirty. Problem still continues.

any advise would be greatly appreciated. By the way, it a luxaire furnace

ben's plumbing 10-15-2012 07:18 PM

Quote:

Originally Posted by bertafamily (Post 1031515)
I set the thermostat and after it reaches temp the fan either keeps running, shuts off and seconds later comes back on, or you hear it trying to draw power and then comes back on minutes later. Now granted, sometimes it will work correctly for a long period of time, however the majority of time it will at least start back up 2 times. also run time varys from a couple seconds to 45 minutes, until i flip the switch off.

Now, someone said check filters, checked and changed although they were not that dirty. Problem still continues.

any advise would be greatly appreciated. By the way, it a luxaire furnace

disconnect the green wire from control board where thermostat wires connect and see if it continues......ben sr

carmon 10-15-2012 08:16 PM

its the wire on G ... it may not be green.......:yes:

ben's plumbing 10-15-2012 08:28 PM

Quote:

Originally Posted by carmon (Post 1031603)
its the wire on G ... it may not be green.......:yes:

come on carmon have faith...its always green :laughing::laughing::laughing: good call ben sr

carmon 10-15-2012 08:46 PM

ya always green.... not aroung these parts.... some guys have zero common sense when wiring control voltage......:thumbup::thumbup:

Missouri Bound 10-15-2012 09:12 PM

Quote:

Originally Posted by bertafamily (Post 1031515)
I set the thermostat and after it reaches temp the fan either keeps running, shuts off and seconds later comes back on


Well the fan should run after it reaches temperature...that's what furnaces do. It should run until the heat exchanger cools. In the event the air temperature in the furnace continues to rise after the thermostat is satisfied it's continuing to burn ( flame) Or the limit control has a problem. Either way you will need a tech to figure it out. When it does come back on, is the air from the vents very hot? I'm not thinking it's a thermostat problem....but I've seen stranger things happen. Have it checked out and get back to us.:whistling2:

bertafamily 10-15-2012 09:46 PM

I will try the green wire. as for the fan keeps running, thats what furnaces do, up till this year it would run for a few minutes after it reaches tem and then shut down. now it sometimes shuts down like it did, you hear an electrical short somewhere and then it clicks back on, sometimes it refires the fan for seconds, shuts down and repeats, sometimes it seems like it will never shut off (the fan that is) until i actualy flip the switch. I've even had me flip the switch, walk away and in anticpation of the house cooling down, flip it back on to make sure furnace and fan kick on when needed. it wil be 1-2 degree above thermostat setting and when i flip the switch fan starts, after sitting for 1-2 hours.

Missouri Bound 10-15-2012 09:59 PM

Can you give a bit more info on the furnace...model number, where it's located, approx. age? You said you hear this short...does it come from the furnace? There are relays which control the fan, limit switches and sometimes a "clacker" type switch as a limit switch. Perhaps you are hearing this. A model number would really help identifying your problem.

bertafamily 10-15-2012 10:22 PM

model number sc100ma, unknown age but we've been in the house since 99 and was here. probably time for a new one, but if i can fix the problem for less than $200, why spend the $1500+ for a new one

Missouri Bound 10-15-2012 10:31 PM

Quote:

Originally Posted by bertafamily (Post 1031699)
model number sc100ma, unknown age but we've been in the house since 99 and was here. probably time for a new one, but if i can fix the problem for less than $200, why spend the $1500+ for a new one

:eek: You don't know what the problem is but you think you can fix it for less than $200. Good thing you aren't in the HVAC business.:laughing:...and $1500 for a new one.....are you living in the 70's?

imautoparts 10-15-2012 11:09 PM

Quote:

Originally Posted by Missouri Bound (Post 1031706)
:eek: You don't know what the problem is but you think you can fix it for less than $200. Good thing you aren't in the HVAC business.:laughing:...and $1500 for a new one.....are you living in the 70's?

Out here in farm country we can usually fix about anything for $1500. Here's a good Grainger unit that a couple of my buddies have had installed recently for around $1500, including labor. Now you travel 100 miles closer to Chicago, you've got an expensive situation... but not around here.

COMFORT-AIRE 80 Puls Eff Furnace Downflow, 75KBtuH, NG




80% Plus Efficiency Downflow Furnace, Natural Gas, 80.5 AFUE, Input 75, 000 BtuH, Output BtuH 60, 000, Voltage 120, Height 34 In, Width 17 1/2 In, Depth 28 13/16 In, Supply Opening Width 16 11/32 In, Supply Opening Depth 20 1/8 In, Available Cooling Tons 3, Flue Dia Unit Has 3 In Connection a 3 to 4 In/ 5 In Adaptor May be Required, Determined By Installation, Side Return Filter Size (2) 12 x 20, With Optional External Side Filter Frame Number 2WYT6

I don't see any reason to think new yet. If you can "hear" the problem as you say, then post as many details as you can and sooner or later you'll find the answer here.

To quote the Hitchiker's Guide, "don't Panic!"

Missouri Bound 10-15-2012 11:44 PM

Quote:

Originally Posted by imautoparts (Post 1031731)
Out here in farm country we can usually fix about anything for $1500.

:eek:But YOU are not the OP. It gets a bit odd when you answer for somebody else. It more than likely confuses the OP. If the OP can do this himself, more power to him. But I'm just trying to figure out his problem now. The installation of an new furnace is another topic.:whistling2:

bertafamily 10-16-2012 08:26 AM

2 Attachment(s)
While I've never worked on a furnace, I am a do it yourselfer, with guidence. I will be working on getting the green disconnected when it acts up, but it did act up and checking air temp out of the bent, it was cool. I do not have central air and thermostat us set to heat and off auto. By the way, i stated i checked the temp out of the vent but didn't disconnect the green wire. the fan had run for over 30 minutes beyond it reaching temp, checked vent temp and then went to diconnect green wire. by the time i got there, it clicked off just as i entered the room. Attachment 58932

Attachment 58933

bertafamily 10-16-2012 08:28 AM

i belive my problem comes from one of the 2 pictures posted. The red, used to buzz when working correctly, now no longer buzzing. The black is where the green wire goes into and seems to be where i can hear the clicking from when i can catch it trying to kick the fan back on.

beenthere 10-16-2012 11:48 AM

Probably a sticking fan relay or fan temp switch.


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