I need to modify my air conditioning system. I hav

[slice2020]

I need to modify my air conditioning system. I have a three story Townhome. The first floor has its own AC unit. The second and third floor are supplied by a larger AC unit. However, the third floor is a large room (essentially a converted attic) which serves as the guest room and usually empty and not worth cooling down. There is a small air intake and three registers on the third floor. There is a large air intake and 6 registers on the second floor.
1- Can I just shut of the air intake and registers on the third floor?
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