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Old 03-23-2011, 05:31 PM   #1
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Replaced thermostat but fan will not shut off


i have had problems with my fan not shutting off on my furnace(gas) so some one suggested i get a new thermostat. after replacing the thermostat the fan continues to run and i dont know what i should do next. any help would be appreciated. thanks

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Old 03-23-2011, 05:58 PM   #2
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Replaced thermostat but fan will not shut off


How many wires are connected to your thermostat and / or it a wireless?
Age /Brand / model of the furnace would help. Does your thermostat have a manual fan switch. Does your furnace have an interior or external summer fan switch?

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Old 03-23-2011, 06:51 PM   #3
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Replaced thermostat but fan will not shut off


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i have had problems with my fan not shutting off on my furnace(gas) so some one suggested i get a new thermostat. after replacing the thermostat the fan continues to run and i dont know what i should do next. any help would be appreciated. thanks
Would be helpful to know manufacturer and model of the furnace or at least approximately how old it is. There are a few things that will cause this problem.
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Old 03-23-2011, 07:01 PM   #4
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Replaced thermostat but fan will not shut off


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Would be helpful to know manufacturer and model of the furnace or at least approximately how old it is. There are a few things that will cause this problem.

its approx 13 years old lennox model c23-31fc-1
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Old 03-23-2011, 07:04 PM   #5
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Replaced thermostat but fan will not shut off


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How many wires are connected to your thermostat and / or it a wireless?
Age /Brand / model of the furnace would help. Does your thermostat have a manual fan switch. Does your furnace have an interior or external summer fan switch?

had four wires connected r, y, g, and w also had a blue wire that was not connected to old thermostat that i looked up and said probably did not need for my furnace. do i need to try and connect blue? bc everything runs fine the fan just wont turn off. has a switch that you can turn the fan off on the furnace in the basement but u have to come down to turn it back on too.
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Old 03-23-2011, 09:50 PM   #6
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Replaced thermostat but fan will not shut off


probably a stuck fan control / relay
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Old 03-23-2011, 10:39 PM   #7
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Replaced thermostat but fan will not shut off


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Originally Posted by gtshorty8611 View Post
i have had problems with my fan not shutting off on my furnace(gas) so some one suggested i get a new thermostat. after replacing the thermostat the fan continues to run and i dont know what i should do next. any help would be appreciated. thanks
well It could be a fan control relay,a time delay realy, or a combination fan control/temp limit control thats sticking. If I knew the type of furnace could help you out a little better!
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Old 03-24-2011, 12:58 AM   #8
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Replaced thermostat but fan will not shut off


When you turn off the switch in the basement that turns off your fan, does it also stop the furnace from operating, if so that switch is probably a kill switch for your furnace.

You could try temporarily disconnecting the two thermostat lines on your furnace that control the fan. (Y & G) If the fan then goes off (when the furnace is cool )then you may have some thermostat wire problems. Put any nails through a wall where the thermostat lines maybe running about the same time that the fan wouldn't shut off???
If the fan stays on with those two lines disconnected then on a 13 year old lennox you are probably looking at a stuck fan relay.
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Old 03-24-2011, 01:33 AM   #9
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Replaced thermostat but fan will not shut off


Ok now maybe were getting somewhere.the switch your talking about could be a bypass to turn on the fan try that but you said you had to come back down in the basement to turn it back on.this is probably a service switch to turn the furnace off .turn it off and than turn the tstat on and see what happens.

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