• Why won’t my furnace fan turn off?

    Nov.25.2008

    What does it mean when my furnace fan won't turn off, and I have to turn off the thermostat, go to the furnace and manually turn off the fan, then turn it back on, then return to the thermostat and turn it back on in order to warm up to the temperature that I have it on?

    J, omaha, NE

    It sounds like you may have a problem with the furnace tripping the main limit. The main limit is a safety control that turns the burner off if it becomes too hot. This could happen for a few reasons. Either the furnace filter and/or cooling coil could be clogged thus restricting air flow, or the blower wheel could be dirty. This could also happen if many of the air vents have been closed or if a return air grille has been covered up with a rug or something.

    When the main line trips repeatedly, some furnace models will go into a lock out phase for up to 3 hours. By turning the unit’s power off and back on, you reset the entire unit and thus the lock out time. This may not be the case for what you have explained but if you have checked the air filter and it is clean then I would recommend you call an experienced HVAC company to check the unit. We do have an affiliate branch in your area called Aksarben®/ARS. If you would like to give them a call their phone number is (402) 331-1233.

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