[scion]

I believe it is in the front lower left side of the A/C condenser, lower grill section. If you get down there you will see it looking at the front of the car.

 

[scion]

The sensor is in front of the A/C condenser which is in front of the radiator. It is mounted low, at the bottom so heat generated from the radiator or a/c will rise away from the sensor. It is easily seen when viewing the front of the car, bottom drivers side.