Help, Furnace fan won't shut off! Been on for HOURS after we had a power outage night before.?

Question

Last night our power went on and off for hours. About every 10 minutes it would try to come back on. Finally it did, but now the furnace fan doesn't stop running. We've turned it to off, the air conditioning is OFF, what to do, why is it doing that, please help, serious responses, or helpful ideas only.

Answer 1

try to turn off breaker and call ac technician

Answer 2

most furnace today are electronically controlled so are the thermostats.

First, try resetting the thermostat, or replace the battery.
some new thermostats use batteries to keep the memory alive.

Next try turning the power off for 15 minutes. this give time for the gas pressure to equalize, in the air conditioner.
if the unit goes on and off to often may harm the compressor.

there is a switch or setting on the thermostat, for "AUTO" or "manual" set it to "AUTO" if set to manual, it will run all the time, AUTO will only come on when the furnace air conditioner comes on or heater

Answer 3

All of the answers are good, probably the thermostat, but possibly the relay that controls the fan contact may have welded togeather. Turn off power then trace the motor leads to the relay, check relay and see if contacts are closed. If so you will have to seperate them and then use nail file to remove all rough edges from contacts. If you cannot get them smooth again you will have to replace relay.

Answer 4

Faulty thermostat.....disconnect or replace battery if it has one. If that doesn't work try a sledge hammer, flip the breaker off first though.

Answer 5

kill power to furnace for 3 mins and restore this should reset control board depends on brand and age

Answer 6

Flip the breaker

Answer 7

be sure your thermostat fan is set for auto and not run