Noisy furnace (in 2 forums)

I want to get into the industry and have been helping friends out, but this is the first time I'm dealing with the furnace rather than the AC unit. Can someone help me diagnose this problem? The furnace suddenly become very loud (makes a low rumbling sound) when the fan is turned on at the thermostat. You can view a cell phone video my friend posted of the fan here: http://www.youtube.com/watch?v=JZxxW...feature=colike. What do you guys think? I am probably going to recommend him getting a professional to do the job, but don't want him to get ripped off.

Note: In the vid, He is pressing the door switch on, then off, then on again - it is not doing this by itself.

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Originally Posted by 2sac

No DIY

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I am not planning to do this myself, but I want to help diagnose the problem to have an idea of what to expect when a pro does come out.

A friends furnace suddenly started making a loud rumbling noise when the fan's turned on. Any ideas on what the problem is? Here's a vid: http://www.youtube.com/watch?v=JZxxW...&feature=g-upl. I am turning the fan on and off via the door switch.

I know exactly what it is. It needs a new part and a pro can get you the correct one.

Thanks for your reply! Hmm, to me, it looks like the fan is a little off balance - is this what you're hinting at? If so, could this be because of dust buildup, or bad bearings in which case the motor just needs to be replaced by a pro? Like I said, I'm still learning and haven't dealt with this problem before, I'd like to know what you see.

Thats not the sound of an unbalanced wheel. Its broke.

Motor bearings or wheel. A sharp tech would have no trouble telling him which. Or both.

How many times do you have to post this James?

Now just in 1 forum.