Starting on Monday I noticed a strange sound coming from the dash. It sounds like an acorn is rattling around somewhere and happens with the AC off. So I took out the cabin air filter, removed the debris and reinstalled.

Well this didn't cure the rattling sound, in fact it introduced a new sound that sounds like a whirrrr when I turn the AC on. Switching from cabin air to outside air makes the sound less prominent but it's still there.

I popped the hood and inspected the air intakes and everything looks OK and clear of debris.

Any suggestions for my next plan of attack ?

Does it sound like this? Seems like it does...


if so, it's a pretty common thing on toyotas. It has to do with the AC servo just becoming of age. There's a fix/replacement for it, but it's pretty extensive. I've just left mine alone.

Grinding/clicking under dash - air mix servo - Toyota Nation Forum : Toyota Car and Truck Forums

Yeah, I think my air mix servo is starting to go. Its pretty easy to tell if that's the culprit if you set the cabin temperature very close to the outside temperature. That way the mixing valve tries to move back and forth a lot to maintain that temp (a little cool, a little hot, no wait that was too much, maybe more cool, ugh now some hot). One guy called it "hunting" because the system is hunting for the right mix and the contacts in the servo are giving bad readings and the computer gets confused.

There are a couple of videos about fixing the servos. They mostly entail removing them and cleaning out the contaminated diaelectric grease and the contacts then re-lubricating and reinstalling them. I might give that a try if it gets worse.

Thankfully doesn't sound like a servo. Attached is a video, the first sound is tough to hear but the new sound is obvious as it sounds like a vacuum cleaner :

https://www.youtube.com/watch?v=J9RvC8ESbX4

Wow.. That's weird... Can you isolate where that sound is coming from? Maybe its your blower motor going out as it sounds like the sound goes up and down with fan speed.


BTW, 418 till empty? WTF.... You lucky bastard... Max i'll see now adays is ~320 till empty...

Problem 2 solved and I can't believe I didn't see it when I removed the cabin filter yesterday. Somehow the PO had stuffed a Starbucks napkin inside there for god knows what reason. Removed the napkin and the vacuum sound went away.

Attached a better video for the rattling sound. It happens with the AC off which makes me hopefully it's not a servo issue. It's driving me nuts and it sounds like there is something rattling around inside some air intake:

https://www.youtube.com/watch?v=zRX7FqEdM9w

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Leaves can make it through the cowl into that space. Could be blower blades hitting one.

Yup.. that sounds like the AC servo. It's trying to hunt for the "right" temperature.

Just to follow up for anyone else searching in the future, this tip eliminated the ticking sound for now:

Mine has been doing the EXACT same thing plus a little bit of squeaking. In fact, I took a video today that I was going to post. Sounds like there's a bird trapped behind my glove box. I'll try this fix out tomorrow to see if it solves the problem.

I have the same sound in my GX470. Its been driving me crazy. Will try cycling the temp up and down tomorrow.