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

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?”

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: We would love to help you out and earn your business!

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

  1. 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

  2. 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!

  3. 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

  4. 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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