A few excerpts:
During the 2nd and 3rd centuries, there was no consensus among church fathers, called “apologists,” about the constitution of the Holy Spirit. Most of them didn’t think it was important. In fact, there was a widespread fluidity of ideas among Christians about it. Some thought the Holy Spirit was an impersonal power; others ascribed full personality to the Holy Spirit.
…it should be understood from creation that the Spirit of God is to God what the spirit of man is to man. Since man’s spirit is not a person as we moderns understand personhood, God’s Spirit must not be a person either. Rather, the Holy Spirit is the Spirit of the Father (Matthew 10.20; Mark 13.11). (emphases added)
Check out the whole thing.