OEM lines have color coded stripes. I had a diagram here. Don't know if I can find it today though.
Only 1 attaches to the engine manifold vacuum port. That is vacuum supply to the controller. The other 2 go on the servo/ pod at water control valve. It is or should be on the right inner fender. Controller calls for heat, one vacuum line opens the valve. Controller calls for air, other vacuum line closes the valve.
