air conditioner wiring for 66 coupe

[lakec]

Need help in wiring my original Ford ac to the 66 coupe I am restoring.  There are three wires coming from the ac unit.  I believe that the black one gets connected to the ignition wire and the other two are grounds (since they have a u-type connector).  Can anyone confirm this?  Thanks.

[Thierry]

Let me know if this can help:
http://metropartsmarket.com/catalog/image_classicmustang_c11_1518.html