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Hello, tell me please a lot about your technical skills background so that I can coach you most effectively.
If the unit out side is running and the thickest copper tube attached to it cool and the rest of the house is getting cooling.... the problem is most likely a stuck or defective zone damper (60%), or a problem with the zone control box, or thermostat.
If you can attach a very clear, well focused photo of the wiring inside the zone control box, and the wiring diagram glued to the inside cover of the blower in the air handler or furnace, I can mark it up with trouble shooting instructions.
We can go from there.