ac wiring harness has three wires and car wiring harness only had two

random tube coming from wiring harness

Not sure about "splice" ANYTHING... that whole harness is a stand-alone unit, with plugs to plug into everything it needs to connect to. It's made that way so that one version of it can be installed in non-AC cars and another into AC ones at the factory. Everything about it plugs into some part of the car in such a way that the car can easily be equipped either way on the production line, according to how it was ordered. It should have a brown wire that plugs into a brown wire under the dash that supplies Acc power to the whole system, 2 plugs that plug onto switches on the control head (1 for the function sw and 1 for the blower sw), a plug that plugs onto the blower resistors, a plug that plugs into the blower high-speed relay, a purple wire that plugs into the blower, a black ground wire that also goes to the motor, a big red wire that plugs into another big red wire that supplies battery to the blower HS relay, a plug with green and blue wires that plugs into the low pressure cutoff switch on the accumulator, and a connector with green and black wires that go to the engine harness. There is some variation in the exact number of green wires etc. at that last connection which sounds like what you're asking about. A good clear photo of both halves of what you've got would help.

The "tube" is not "random". It's a vacuum line, that carries vacuum from the vac reservoir and check valve, to the control head. The control head then routes vacuum to all the little motors (diaphragms) that sends air out the various vents. There's a little "harness" of colored rubbery lines under the dash that carry the vacuum around.

Black to black, blue to blue. Not all that hard. Use connectors. DON'T "splice".

I'm gonna GUESS, since you didn't tell us, that the cut off wires are the car's, and the connector is the HVAC harness. In which case you need to find the green wire in the car harness. Would have gone to the compressor. Maybe got pulled out during prior "improvements" and thus need to be reinstalled. Try to find it first.

There sure does seem to be ONEHELLUVALOTTA generalized electrical SODOMY going on in this car. Some people should go to federal pound me in the [rectum] prison for even picking up a pair of dykes, let alone using them against their car's health.