Strange sound from inside dash...

When I'm stopped with the car idling, I hear what sounds like either the Air intake selector or Air flow selector in the Air conditioning system is cycling back and forth almost like a flow deflector flap is opening and closing. When I change selections using the air intake selector; say from vent to floor, no change, sounds like the cycling continues. I'm only assuming its the Air conditioning system, could be something else, but it appears to be coming from inside the dash in that general vicinity.

2003 PreRunner DoubleCab

 

I have the same truck and I think I have the same sound from what I can get from your post.

 

The bad thing is I don't even know how to go about troubleshooting. What exactly does yours sound like? With mine, you only notice it when the car is stopped and idling. It's a very subtle sound and it seems to cycle back and forth (whatever it is) about every second to couple of seconds over and over. It sounds like a flap or a door that keeps opening and closing on top of a hollow opening. It's Very hard to describe.

 

Mine does it went the ac is on. I would say it kinda sounds like something being turned on and it has kind of like a hissing/buzzing kinda sound to it. its the best i can describe it. sorry. And I can only here it while im stopped.
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there is an adjustment you can make that will help, turn the knob above the a/c panel clockwise until you can no longer hear it

 

Is it the cold / hot climate control knob?

 

There was a TSB published concerning interior noises. TSB NV006-02

 

he means the fan/off switch.

 

Mine has that sound its from Mud in the AC Idler bearing. It sounds like there's dirt grinding in it.

 

I mean the volume knob!

 

oh sorry. Thats what i do.