[jerryez]

My TiVo Roamio OTA has started making a whiring sound like a fan noise. Do you think it is the hard drive or the cooling fan? How do I tell the difference? Where can I buy a replacement fan, if that is it.

 

[JoeKustra]

Where to get roamio basic or OTA cooling fan replacement

skip to near the end. Buy it with the tools.

Also see: Where to get roamio basic or OTA cooling fan replacement

BTW, once you get the cover off, you can unplug the fan to test.