Did King Asa go to Heaven?
"For I know nothing against myself, yet I am not justified by this; but He who judges me is the Lord. Therefore judge nothing before the time, until the Lord comes, who will both bring to light the hidden things of darkness and reveal the counsels of the hearts. Then each one's praise will come from God" (I Corinthians 4:4-5).
God did not tell us what His judgment will be. Asa did many things right during his lifetime, but he also did some sinful things. It is not up to us to second guess God's decisions.