I have a Coleman gas furnace, the pilot is lit, the thermostat is turned up, the blower fan turns on runs for approx 30 seconds then shuts off again....I dont know what to do any suggestions?
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The fan limit switch probaly needs replaced. -
Ok...that gives me an avenue I havent looked at yet. Thank you. I am trying to do this myself will that be possible or is this not a DIY project? Its getting cold here in Iowa and this is all new, furnace worked just fine 4-5 mos ago. I guess I need to ask also how do I go about figuring out if it is the switch?Comment
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the limit switch turn the blower on when the bonnet temp reaches a set point, it can either be adjustable or fixed type of device. does it run continually when you put the thermostat to blower on??Is it beer thirty??Comment
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I dont have anything on the thermostat that controls the blower, as in an automatic/on. The only switch I have for the blower is an on and off switch right there on the furnace. I havent found a way to keep the blower on it just shuts off after 30 sec -1 min...Comment
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you have a model numberIs it beer thirty??Comment
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Coleman Presidential Gas Furnace Model #7680
Robertshaw-Grayson #7DOC4F005
Blower #7660A590Comment
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Maybe this will make it clearer for you... is this a MH furnance??
Temperature switches determine when a blower runs and when it doesn't. Names for these switches, which vary from furnace to furnace, are called fan control, limit switch, upper limit switch or lower limit switch. A furnace may have more than one of these switches.
limit switch
When the heat exchanger gets hot from the burners, either the fan control, limit switch or upper limit switch will tell the blower to turn on at a 'pre-set' temperature. When the burners are no longer lit because the call for heat by the thermostat has been met, then either the fan control, limit switch or lower limit switch will tell the blower to stop once the temperature inside the heat exchanger has cooled to a 'pre-set' temperature. Also remember that the burner ignites (comes ON) before the blower starts and extinguishes (goes OFF) before the blower shuts off.
If your blower isn't functioning properly, a possible cause is one of the above temperature switches. Do keep in mind that transformers, thermostats, fan relays, circuit boards and capacitors also affect how a blower functions and you could have a possible problem with one or several of these components. Calling a competent technician is always the most recommended way to troubleshoot your furnace problem.Is it beer thirty??Comment
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Yes it is.
Thank You. I think you are right and this isnt something I can figure out myself Im gonna go ahead and call a repairman and have him take a look. Thanks again for taking the time to explain this all to me.Comment
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I called the repairman and he says it could just be leaves/old bird nest stuck in the exhaust causing the blower to overheat and shut off......Im gonna try that first rather than pay him to come clean a bird nest out of a pipe.......but if that doesnt work Im calling him backComment
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I have a feeling you will be calling him back.Comment
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Sorry to revive an old thread, but this problem is exactly what I'm experiencing with my older Singer model furnace.
When the thermostat is set to the ON fan position, the blower will run continuously without cutting off. However, if you set the fan position to AUTO, it will kick on for approximately 30 seconds and turn off. It cycles like this the entire time.
I don't believe the blower is going out because when you switch it to cool, set the fan position to AUTO, it works fine.
Does anyone have any suggestions? Thank you.Comment
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Guess what .... after changing the thermocoupler twice with limited benefits I finally called the furnace guy and he fixed it. But what I thought was the kicker was what the problem turned out to be it was a dang spiders nest in the burner...I thought I would let you all know we were all wrong but at least it is up and running
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