I have a Bryant 355BAV042060 natural gas furnace that I had to replace the draft inducer motor assembly on at the beginning of 2018. It's been working fine in the winter seasons since then keeping the house warm. For the last year or so, it's been making a noise when blowing heat. I can hear this noise through the air vents, and also when I'm outside I can hear the noise coming through the furnace air vent/exhaust, echoing off the neighbor's house into our back yard. It's gotten progressively louder over the past. When it's just the fan (circulating air), the noise isn't there.
I took the cover off and it looks like the noise is coming from the draft inducer motor assembly that I replaced six years ago that's making the noise. Here's a video of the draft inducer motor assembly making the noise.
I'm not sure the noise indicates a problem at all, but it wasn't there for the first four years, and it's getting louder, so it seems like a symptom of something not right. I assume the issue is a bad bearing. When the draft inducer kicks on, the pitch of the noise starts low and increases as the speed of the draft inducer does, and when it turns off, the pitch slowly goes down as the draft inducer slows down.
Identify the problem. Does a bad bearing indeed seem the most likely cause of the noise?
Identify the cause. In my head, it's possible that a bearing just went bad. But it's also possible that I (regular DIY guy, no formal HVAC training) installed the part incorrectly. I followed the instructions, and used the special Momentive RTV 162 high-temp silicone to seal up the collector box as instructed. But I also starting using MERV-13 air filters maybe 18 months ago, and I'm not sure if that may be too restrictive of a filter for my furnace.
Identify the solution. If this is indeed a bad bearing, is it likely it can be replaced? I've found a couple YouTube videos where people are replacing bearings, and I do have a puller. Or would the recommendation be to replace the entire assembly again.
The draft inducer motor's bearings are sealed, so no maintenance to perform on them.
Pushing on the motor while it is running does not affect the sound. Video.