What is causing this sound?

It sounds like it is originating under and behind the passenger glove box. It makes with a/c on and off. Almost sounds like a gurgling and tapping sound. Heater core? Here is a recording:

https://youtu.be/3tgmciAs5dI

 

Sounds like something is hitting the blower motor fan blades.

 

But if the blower motor is not engaged since the a/c is off...why would the fans spin?

 

At 35 seconds i briefly turned the a/c on and turned it off after a few seconds.

 

Check your cabin filter. I had a squirrel drop some nut shells down in my Camry vent & torn my blower motor fan up.

 

Could be the servo for the air inlet. See page 34 item 26. You could try unplugging it and see if the noise goes away.

 

Sorry, you said with fan off. Some vehicles the fan still runs on low with the switch off especially if on defrost.

 

It doesn't have a cabin air filter

 

Blend door actuator. Try turning your hot/cold knob back and forth about a dozen or more times. Sometimes some dirt gets caught in the gears and they need to be worked a bit to clear them out. This is why it happens with the blower motor off.

 

Turn your hot/cold adjustment knob all the way to the right and then all the way to the left. If the noise stops it’s probably the servo damper.
Good Luck man and hope you get it resolved.

Thread I posted on this...

https://www.tacomaworld.com/threads/air-servo-damper-no-2-possible-aftermarket-part.500522/

 

Man we are thinking alike!! I can tell you’ve been there done that!

 

Yeah the noise will always come back at some point though. Eventually Ill replace the actuator but for now Im not concerned with it.

Also, I see youre in Bentonville. I will be camping there in a few days. Any good eats in town? Mainly plan on hitting up the mountain bike scene that a lot of riders seem to rave about.

 

This was the solution. I tried this after i read about the servo motor, and figured it would affect it. Thanks yall, glad its nothing serious.

 

Sounds like you may be hitting the Pig Trail up to the Eureka Springs area. I’ve been on that a few times on the FJR during Bikes, Blues, and BBQ.
Not sure what you like, but there’s the “Flying Fish” restaurant in downtown Bentonville, or you can go to the Promenade Blvd. area (exit 82 off of I-49) where there is a “Twin Peaks”, “5 Guys”, “Long Horns”, and many more.
There’s also a Cabela’s/Bass Pro Shop in that same area.

 

Just noticed this in wife's 2004 highlander as well...