Testing the power connection to the fans and fan operation itself
The fan's can easily be tested for operation and power, but it is bit tricky since you may not make any mistakes and mot touch ground with a hot (12v) wire. Remember that you are pulling 25amps or more upon connecting the Fan.
On the fan controller power stage (the one with the fins in the nose of the car) you see a round connector with numbers 1-8 on them. Disconnect and turn upside down. You see the holes that match the pins on the power stage. Ok, on the connector the 12v arrives for fan1 and for fan2, and power out is wired to power the Fan1 or Fan2. The Fans are connected to ground elsewhere. So the idea is top bridge 12v for Fan1 to power out for Fan1, and the same for Fan2.
Bridge 1-8 on the connector of the power stage which makes the Fan2 run, and is the right side fan
Bridge 4-5 on the connector of the power stage which makes the Fan1 run, and is the left side fan
Left and right are seen in the engine
bay looking from front to rear of the car
Here is a picture that helps understanding: