2008 XC90 Bad Fan or not?

[ingydrummer]

Im a little confused with the correct way to see if cooling fan is bad or not. There are 3 different posts in the socket, the hot, ground and the tiny prong.
When testing the harness itself the hot is live even when the key is off. So how do I check the fan itself? I already put the hot from fan directly to the batt., and then grounded the ground and I get nothing from the fan. My question is do you have to use the small prong when testing the fan? Help, Im stumped and don't want to buy the fan until Im sure its bad. Thanks in advance.....