My inside hvac unit believe it or not only rattles at night I know that's crazy. whenever I remove the filter it seems to suck in more air and stopes rattling the moment I place the filter back the rattling begins. Mind you the air filter is a new filter. Crazy thing is that throughout the morning and evening there is no noise or rattling only at night. The rattling sounds so loud that you would think the motor is going to fall off, but again only at night . Has anyone had this kind of problem before?

  • Are you saying the filter was rattling or the rattling was coming from somewhere else in the ductwork or cabinet and increasing the airflow by removing the filter stopped it? – topshot Sep 18 '16 at 16:42
  • Sorry if my post did not make since , but the motor or blower seems to rattle a lot at night not sure why. Everytime I remove the airfilter the rattling aka motor seems to stop rattling. As soon as I place the filter back on it begins to rattle again. I wish I could upload a video so that you can see what I mean – Alex Sep 18 '16 at 19:56
  • The only at night part is truly bizarre. What is the brand/model number of your furnace? You could post to youtube or some other service and then post the link here. I wonder if it runs at some other speed at night for some reason and hits a resonant frequency of the cabinet. – topshot Sep 18 '16 at 23:39
  • It's a carrier 8000 , yes I know it gets annoying at night hearing all that rattling going on. – Alex Sep 19 '16 at 0:05
  • youtu.be/kX_RnDtaoaI I just uploaded the video on YouTube – Alex Sep 19 '16 at 0:16

I don't know why it would be diferent at night unless you have a multi speed fan. Or the house is opened up or closed more. If a direct drive check the motor mount bolts to make they are secure and the squirrel cage to verify the bolts are not loose. If a belt drive the belt may need tighting checking the pulley on the motor and squirrel cage also would be my checks.

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  • Yea that's why I don't know what could be going on it doesn't rattle during the day just at night I have a video of it if only o could post it on here – Alex Sep 18 '16 at 19:58
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    If it starts and stops at regular intervals, like day / night, it sounds like the thermostat. It needs to be re-programmed. Maybe it's calling for more heat at night and the second stage fan kicks in. – Lee Sam Apr 7 '17 at 5:19

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