'21 Model AC Buzz

Hello, thought I'd give this a shot and see if anyone can help.

I just got a brand new 2021 TRD Pro 4R and after about the first 500 miles of driving it developed this very slight, albeit very annoying buzzing sound from the passenger side of the dash/glovebox area. It primarily does it on a cold start but will also do it when it's idling in park thru out the day intermittently.

So far I have had two dealers look at it and one replaced the blower motor fan and the other flushed and recharged the AC lines. Neither of these have fixed it. Next course of action is to take it back to the dealer and leave it with them for however many days to pull the dash and examine everything more closely. Supposedly one of the technicians from Toyota Corporate is even going to come take a look as they say they have never had anyone else complain of this problem before. Here's a link to some video I recorded of it.

https://www.youtube.com/watch?v=tpwy8WuiLqw

Has anyone had any experience with this and came up with a solution?

 

Is it coming from inside our outside? It almost sounds like it could be something related to the engine like a mount, or something rattling due to the engine.

 

It comes from inside. Few things I have noticed during my trouble shooting. If I turn off the AC it stops, if I'm cruising around it stops, and if I open the passenger door it stops.

 

Mine did the same 'new'. I was convinced it was coming from the fan motor so I ran the fan on high for a long period of time(a few hours during a long trip) and that took care of it. fwiw

 

I’m 99% sure it’s the fan motor as well. I’ve thought about ordering a after market one and swapping it myself. Now that you mention it the sound also goes away when the fan is on a higher speed but that may just be because the noise of the air circulating is greater. ‍♂️

 

I've noticed the same thing. I may try running it on high for a bit and see if that helps make it go away. I've only had mine a few months and have only run the AC on low fan and it doesn't really make any noise. If I turn it up mid way or so it starts to make the same buzzing and mainly at idle too. Or because the vehicle isn't moving its just more noticeable.

 

Once I thought it completely through it dawned on me that the fresh air intake filter is paper and at certain fan speeds it was likely the paper filter buzzing. None the less, after doing what I mentioned above......it stopped.

 

Does it change any on recirc? Seems like a factory issue given so many are experiencing this. Wonder if it could be a tiny piece of insulation coming into contact with the fan?

 

Flush and recharge the ac system. Gotta wonder how one jumps to that as the likely culprit. Seem like quite the hail mary.

The cabin filter theory might have something to it. I would take it out and run it without for a while to see if it changes anything. While you are in there, be sure to check for twigs or other nesting material.

If it’s not that, then the only other logical step is to replace all of the valve guides and timing chain.