Below is a picture of the evaporator sensor on my 2003 V70 - should be the same as your's I would imagine. When you drop the drivers side under-dash kick panel you can look up above the gas pedal a few inches and the sensor is poked into the LH side of the evaporator box. You will only see the rectangular plug part of the sensor until you pull it out - just a snap-in friction fit.

If you want to test the sensor resistance, from what I'm told a good sensor will read 10K ohms +/- 200 at 32 deg F and approx 3K ohms 77F. My old one was waaaayyyy out of whack. But when I got the new one in the mail I had loaned my one-and-only ohm meter to a fellow worker so I couldn't verify the resistance on the new part. All I know is that I installed it and now the compressor cycles as designed.

When you reinstall the sensor, make sure you clock the connector to the same orientation as it was originally so that the business end of sensor is adequately sensitive to the cold evaporator. In my case the connector was straight up.