Repurposing server parts

Repurposing server parts

I've a few fans from an HP 7000 enclosure that are surplus to requirements. Remembering that the demonstrator at HP was very proud of the efficiency of these, I though that rather than waste them I might repurpose one or two, for example to cool an aircooled engine when stationary in traffic on a hot day. The casing says 12vdc but uses a PCB connector with around a dozen contacts of various sizes, however if I strip the housing off, there are three wires to the fan itself: blue, red and yellow.

I've no intent, nor the skill or knowledge, to replicate the fine control and reporting that the onboard administrator gives these fans for their intended setting, just a simple connection to the 12v running on the vehicle is the likely solution (via a switch or rheostat), and a search of the 'net reveals nothing about what wire is effectively the +ve, -ve etc, and there being three puzzles me as I might be able to get some measure of control, perhaps half and full power, but that's just a guess.

Anyone any ideas on how to logically find out, or knowledge of the HP wiring colours? I'd prefer to avoid "trial by possible destruction" as the means of finding out, but if that's what it takes in the end...

p/n 389554-001, inside a housing/unit p/n 389537-001 if that helps.

Thanks