the tension can change on the drivebelt when the a/c is switched on. It might be the belt tensioner going bad. It's not rare for those to die on our engines. Might want to look closer at that.

 

What happens when/if it goes out ?

 

its just the compressor

 

you lose the tension on the drive belt and then it will just come off. It clacks more and more as it dies (the belt tensioner). Might get yourself a mechanics stethoscope (got mine at harbor freight for $4) and probe around while the car is running to pinpoint the noise (don't get hurt of course, while car is running and you're probing around)

im not saying its not the compressor making noise, just pointing out that other things make that noise too when they die.

 

Mine makes that noise also, and only when the AC is on. It's been doing it for a solid 6 months now, but when I took it to the Toyo dealer, they said they didn't notice anything out of the ordinary either. My sound isn't as prominent as yours, but they didn't seem concerned (and considering I had already spent about $700 during that visit for a new O2 sensor and speed sensor to be replaced, I'd think they'd jump on it if they thought it was another way to get my $$$ lol)

If you do find out something though, let us know! I'll definitely be going back if so

 

I will keep you post Amber. I am going back either thur or next week.

 

kinda sounds like the vacume switching valve to me....the little box thing with the wires for the maf sensor.