Blower keeps running even after thermostat is in off or in auto? The forced air unit stays on even after temp setting is reached or will switch thermostat switch to off. The heat stops but blower stays on until I turn the breaker off.

Could be a bad blower motor resistor,mounted by the blower.

check the operators manual but you will probably find that the fan will keep running so that the air in the room is circulated past the thermostat so that the temperature can be monitored and the compressor switched on when the temp reaches the upper limit

A lot of units have a switch by the blower unit. It switches left or right. One way is automatic running from your thermostat and the other stay running...You can alway turn the blower off from your main breaker box..But that want fix the problem...If I had to guess..You have a small wire loose or disconnected in your thermostat...Take the cover off and look for small wires.. Sometimes these wires get broke moving the settings up and down...Find the lose wire and reconnect...You can replace the thermostat but you will still have to connect the wires to the new one...I have seen people with weed eaters cut a outside wire by the units that caused the blowers and units stay on...Hoor this helps

Most T-Stats have a On / Auto on a forced air system. On means the fan will run all the time even if it is not calling for heat. Auto only runs when calling for heat. Does the fan turn off in the auto mode at all? To test it...BE SURE THE FAN IS IN THE AUTO MODE ON THE T-STAT... Turn the thermostat all the way down and keep it there for appox 15 mins. If it is wired properly and the fan limit is set properly the fan should turn off. If it doesn't it is not the thermostat were the problem lies.

Most forced air units have a fan / high limit switch. There is a setting on the switch for the fan to turn on and a setting for the fan to turn off or it has a setting and a differental switch for it to turn off/on. Example - the fan comes on when the temp in the heat exchanger reaches 110 degrees F and will shut down at 95 degrees F after the thermostat is satified...this would hav a differental of 15 degrees F. It may be set to low and the fan continues to run long after all of the heat has been removed from the heat exchanger. This in turn will cause cool air to be coming out of the registers.

Could be either, Thermostat or fan relay on unit. Make sure thermostat fan switch is set to auto

I want to give a simple explanation before I go any further. On the heating side of a unit even though tthe temp has satisfied the thermostat, the fan will run until it cools down the plenum where the air flows from the air handler. There is a bimetal switch called a fan limit that operates the blower when the plenum reaches the temp set on the fan limit switch. Now if your fan keeps running even after the plenum chamber has cooled down, then you could have a fan limit switch that is stuck in the run position and must be replaced in order to correct the problem.

Hi!!
If when the desired temp. is reached, the compressor and condenser motor (outside unit) will shut off but the blower in the inside unit will keep working when the thermostat is set to Auto, the problems could be 1 - thermostat unit defective, and 2 - blower motor starter relay defective.
Good Luck!! Don't forget to rate this post!!

Hello

Okay did you check your thermostat to see if you have the fan switch on auto? The switch must be on auto or the fan will continue to run. If the thermostat fan switch is on auto then there is a malfunction in the thermostat probably. You can go to your forced air unit and on unplug the unit. That way it will not turn on at all, because the forced air unit is controlled by the thermostat. Hope this helps.

you have either a bad thermostat or bad controls in the units unplug the furnace make sure the outside unit shuts off turn off the thermostat plug back in if it all starts with the thermostat off you will need service thanks for the high ratting keeps me helping for free.Tom

If you have a standard thermostat the fan switch is for the air handler only. It completely over rides the thermostat for most settings. Now lets see this is what I'd expect:
fan switch on Indoor fan runs all time
Fan switch auto Indoor fan only runs when thermostat is set to cool or heat and the thermostat is turned up above room temp for heat or below room temp for cooling. In both of these modes the furnace blower comes on and stays on til the room temperature is satisfied. The outdoor unit only comes on for AC the out door unit will not come on for heat or the "on" setting on the thermostat. See exception 1 & 2 below...

Exception 1- (in a heat pump the out door unit runs in both heat and cool mode unless it has emergency heat turned on then it will not come on outside in the heat mode, and depending on the type of heat pump and furnace or air handler it is). A heat pump thermostat usually has "backup heat" and an "emergency heat" setting switch on the thermostat.
Exception 2 - On some thermostats they are made to cycle on the heat if the temperature reaches a preset temp (around 50'f usually but definitely by 40'f). This mode prevents freezing when if instance the homeowner is away or while the home is under construction. In this mode the fan inside can run but the heat usually comes on with it.
Exception3 - On some electric furnaces the heating strips may be individually controlled and thus not all come on at one time. This may give the feel of no heat especially if the room is cold.

Now there may be other exceptions but Ive tried to give you a heads up on some of the most common ones.
If you need more help please post more specifics about your unit/system as to for sure what switches are set to what setting and what is happening with each. My first though was that maybe your system is OK and you needed to know if the thermostat was working properly.

If this helpd you understand your problem would you please give me as hifgh a mark as you can. Thnaks for using fixya and good luck.