I always buy mine from Ross-Tech VCDS

The fans come on with the lower radiator outlet and main coolant temperature senders unplugged because then the internal controller in the main fan V7 is no longer receiving the digital coolant temperature signal from the engine ECU along the yellow/lilac wire and so as it knows the engine is running by the signal along the blue/red wire, the fan controller assumes the engine is overheating and puts the system into emergency mode.