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Top 10 Reasons Why the Blower Fan Motor will not come on. Furnaces, Air Conditioning and Heat Pumps

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Questions: We have many people ask, “how can I find out why my fan blower motor is not working?” “Why does my fan motor not work when I turn on my furnace or air conditioner?” “Why will my furnace’s blower motor not come on?”

Answer: I found a real good Youtube video made by ACServicetech that explains the top 10 reasons why fan blower motors will not come on. ACServicetech goes over what to look for in the system, components that fail most often, how to test the components, where to take readings with a multimeter as well as other tips! This is a great video that I would highly recommend that you watch if your fan blower will not come on. Many thanks to ACServicetech for making this informative video! If you have any questions please email us anytime. Our email address is arnoldservice@gmail.com We would love to help you out and earn your business!

You Can Search Our Site for More Troubleshooting Problems with Answers, Heating, Air Conditioning Parts and Supplies in the Google Search Box Below:

20 thoughts on “Top 10 Reasons Why the Blower Fan Motor will not come on. Furnaces, Air Conditioning and Heat Pumps

  1. Hi Steve,
    I have an older Maytag furnace that will fire up but the blower motor doesn’t come on, after a minute the the limit switches will turn of the furnace because it will get to hot. I already replaced the motor, the limit switches, and the motor board but I still have the same problem.
    The green light is on and the red light flashing, in the manual it says there is a “pressure switch closed” problem. I tested the pressure switches and they are fine. Do you have any suggestions? Thank you!
    Markus

    1. Hi Markus! You will need to test with a voltmeter and see if your fan motor is getting the required 110 to 125 volts AC out of your control board to start the motor. I would suggest setting your thermostat to the “Fan ON” position. You should be getting 120 volts out of the control board. You can test by testing with a voltmeter set to “Volt AC” between the high-speed blower wire (usually black) and the white neutral wire. If you are getting 120 volts to the motor and it is not starting then you have a blower motor problem and either need another new blower motor or a new blower motor run capacitor. If you are not getting voltage to the blower motor out of the control board then you probably need a new control board again. Make sure you are getting 24 to 28 volts AC between the G and C (com) thermostat wires on your control board when you have the thermostat set to “Fan ON”. If you are not getting 24 volts between G and C then you have a thermostat or a thermostat wire problem. I have heard some people say that if you have a Honeywell Smart Valve, gas valve installed and it is defective then this can cause blower motor issues where the blower will not start. Since the control board is saying that the pressure switch is closed I would suggest making sure that your pressure switch is opening up (not allowing current to flow) when the draft inducer is off and closing (allowing current to flow) when the draft inducer is on. I hope you can easily find and fix the problem. Steve

  2. i have an amana furnance and the blower works on a/c mode, however the blower will not come on in heating cycle

    1. Hi Rodney! Most of the time on Amana furnaces the blower coming on in the heating mode is timed by the control board unless you have a really old furnace that a mechanical fan center relay like the ones we sell on the following page: https://arnoldservice.com/product-category/fan-blower-controls/honeywell-fan-and-limit-controls/ You might need a new control board or if you have an old furnace a new fan limit control. I hope you can easily find and fix the problem. Steve

  3. Hi Steve, so I test my transformer and it show that I have no 24 volts coming out of the transformer. The issue was I have two identical units. unit #1 is the one with no 24 volts coming out. Unit #2 is working normally. What i don’t understand was, when I move the transformer from unit #1 and connect to unit #2 I have a 24 volts coming out. But when I connected the transformer from unit #2 to unit #1, it show zero volt. I know that both the transformer is working normally on unit #2 and both show zero volt at unit #1. Both units show 120 volts going to the transformer. Any idea what is the problem here. thank you

    1. Hi Ko! I am sorry, but I do not know what could be the problem other than the load when applied to unit #1 is too much for the transformer or you have a short on unit #1 and that is taking all the voltage away. If you have 120 volts on the primary and 24 volts on the secondary in one transformer and not the other it seems like the transformer might be at fault if there is a load applied on both units. If there is no load applied then I have no idea what the problem could be. I hope you can find and fix the problem soon! Steve

  4. Great video.
    My question is why does my blower work for a few hours and then start tur ing on and off? I will turn it off for several hours and the tur it back on and it works for several hours then it starts going on and off every 5 – 20 seconds. I had the thermostat replaced so it’s not that.
    Thanks

    1. Hi Nancy! This sounds like your motor might be over-heating. I would like to suggest that you make sure if your motor has a capacitor that the capacitor is good and up to specs. If you have a high efficiency ECM motor then you might have a motor module going out. You might need a new motor module on ECM motors. If the capacitor is good and you still have the problems then you could have motor windings that are going out and you might need a new motor. Also, sometimes a blower motor relay on your control board might be going bad and you might need a new control board. The only way to test and see if it is a blower motor relay would be to test with a voltmeter to see if the motor is getting 110 volts to the motor when it starts going off and on. I hope you can easily find and fix the problem. Steve

  5. Hello, I have a blower motor that will not come on when the AC switch is turned on, but if I go out and throw the main breaker in the CB Box it will come on.

    1. Hi Glenn! This sounds like you could have a control board problem since the problem is erratic. We have a post about this problem on the following page: https://arnoldservice.com/problem-fan-will-not-come-position-fan-will-not-come-turn-thermostat/ You will need to test with a voltmeter to see where the problem is located. I hope that you can easily find and fix the problem. Steve

      1. Hello, I have heat pump unit with a backup auxiliary heat. My blower will not come on neither heat or cooling mode. Blower will no running on neither auto or fan. I’d jumped the motor and is working. My capacitor and transformer is also good too. I have 120V incoming power to the motor too. Need help, any idea?

      2. Hi Ko! If you have a thermostat with batteries I would suggest making sure the batteries are good. Next, I would check with a voltmeter set to “Volts AC” and make sure that you are getting 24 to 28 volts AC between the green and C (com) wires on your thermostat wires with the thermostat calling for the fan to be on. If you are not getting 24 volts between these two wires then you have a thermostat problem or a thermostat wire problem. If you are getting 24 volts between G and C then you probably have a fan relay problem or sequencer problem. Some of the heat pumps with electric heat control the blower using a sequencer. Some control the blower fan with a relay. You should be able to find this relay or sequencer by tracing the blower motor wires back to the relay or sequencer. If power is going into the sequencer or relay and not coming out when the 24 volts are applied then you have a relay or sequencer problem and the sequencer or relay will need to be replaced to get your blower running right again. I hope this helps. Steve

  6. My blower runs continuously even if the unit is off the relay switches are good. Do you think thermostat is bad.

    1. Hi Fred! Most of the time blowers run continuously because the limit or one of the rollout switches is open. The furnace’s control board thinks that the furnace is overheating so it runs the blower. I would suggest that you check your limit and rollouts to make sure they are all closed with a voltmeter. You can check to make sure it is not the thermostat by taking the Green wire off the thermostat connection or taking it loose from the furnace’s control board. A shorted thermostat wire can cause this too but it is very uncommon. A control board relay where the relay contacts are welded shut can cause the blower to run continuously too. You would probably need a new control board if the relay on the control board is welded closed. I hope you can easily find and fix the problem. Steve

  7. Steve,, just had a new 3 ton Lennox heat pump and matching air handler installed couple of weeks ago. The blower is suppose to run , according to the manual, for 45 seconds after the thermostat is satisfied also shutting down the outside unit/compressor. Well mine don’t. When compressor shuts off with a satisfied thermostat my blower motor shuts off mediately too. Now here’s the kicker,,, it has given me what I call “the residual” blowing ,45seconds, a small handful of times in the past couple of weeks but more not than yes….. sounds like a short??? Well the installer says over the phone its my thermostat and I say blower relay of which I confirmed with tech support from Lennox that the blower relay controls this 45 sec delay off in cool mode. The installer wont come check it out as I have told him he’s not changing my only 2 yr old thermostat out…… I don’t see how my thermostat controls the 45 sec. residual blower? Any suggestions to break the tie here???? thanks doug f.

    1. Hi Doug!
      I have never heard of a thermostat that controls the off time on the blower. I would think that you need a new control board on your air handler. I would like to suggest that you make sure all your thermostat wires are good and tight. In most cases the air handler or furnace control board controls the blower on and off time. I hope you can get this fixed free of charge since the parts should be under warranty. I hope you have a great day and week!
      Steve

  8. Very helpful and easy understood.Thank you so very much.

    1. Thanks so much for your response! Glad to hear that the post was able to help you out! God Bless you and your family today and always! Steve

  9. Sweet, direct easily understood and no rambling on

    1. Thanks so much for your kind words, Kevin! God bless you and your family today and always! Steve

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