Furnace Blower Motor Constantly On

Old 12-29-17, 07:04 AM
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Furnace Blower Motor Constantly On

Hello guys, I have a RUUD Silhouette II furnace that the blower motor keeps running after the call for heat has been satisfied. I have replaced the filter and the upper limit sensor. The flame sensor has been cleaned and does recognize the presence of flame.The roll out sensors are in good condition and are not tripped. The thermostat has been replaced about four months ago and there are no shorts in the wiring. The furnace would come on and run for a while and then go thru it's shut down phase( flame off and motor run to dissipate hot air off of the heat exchanger) then the start up cycle would come on again and then the furnace would run again and the shut off phase would start but then the fan stays on. I'm not sure what else to check. Any suggestions? Thank you
Old 12-30-17, 06:59 PM
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you said the stat was replaced and there are no shorts.

regardless, i would disconnect the g terminal wire at the control board and see if the problem continues.

a open high limit switch can cause this problem too. but it should eventually close and the continuous fan should stop - the heating cycle will restart and it will do this until the stat is satisfied. high limit open due to overheating, not bad high limit.

Do check your filter, blower wheel for dirt, vents (open and not blocked?).

Do you have a thermometer with a stem and a multi-meter? Does the control board have a flashing led? that can tip you off too.
Old 01-01-18, 05:30 AM
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How did you solve this problem

I have a similiar problem with a York furnace, how was you problem solved.
Old 01-01-18, 10:13 AM
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@Bilhar..... every furnace is different. Some use a heat sensor to start the blower, some use a fan/limit control and the bulk of the others use a timed control board.

Please post the model number for your furnace and then I'll make this into its own thread.
The model number can be found on an ID tag inside on the side wall near the burner.

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