Furnace Exhaust Fan Won T Shut Off

This article describes what to check if the furnace or forced air blower fan does not stop when you expect it to do so.

Furnace exhaust fan won t shut off. Forced air heating or cooling air handler troubleshooting. If your furnace goes off on high limit or if one of the rollout switches are open then the furnace fan will run all the time because the furnace control board is telling the furnace that the furnace has over heated and the fan runs to cool the furnace down. Furnace blower fan wont turn off fan select switch on the thermostat is in the manual on position a control wiring problem where the insulation on the wiring is worn off a bad relay fan sequencer relay fan limit control or circuit board with contacts sticking this depends on the type. Why does my furnace fan keep running.

These same diagnostics also aid in air conditioning blower assembly diagnosis when an a c blower continues running. If it s enclosed bang it on your hand to jar them open. If that doesn t work another possible problem could be the limit switch for your blower but this would need to be serviced by an hvac technician. These two settings are for continus fans no matter what.

If your thermostat s fan is set to on then this is likely your problem. Blower fan won t shut off. It s contacts probably welded or burned closed. It s normal for the fan to kick on a couple of minutes before heating starts or to stay on for a couple of minutes after cooling stops but your fan shouldn t run for hours on its own.

Blowr fan won t stop. On the whole the temperature control switches cannot be adjusted and are to be changed if they are defective. Your hvac fan should turn on and off with the rest of your heating and cooling system. If the furnace blower does not turn off turns off too quickly or not quickly enough as it blows cold air towards the end of the heating cycle then the glitch is possibly a bad temperature control switch.

If you can get into the control box look for a small relay follow the fan wires to the relay. Check to make sure the limit and rollouts are all closed. If you can use a screw driver and pop the contacts open. The exhaust fan relay is hung up.

Auto will shut off the fan low and high will not shut off the fan. Locate your fan limit switch your fan limit switch is located inside the furnace panel cover usually near the.