Do Angels have Free will? If they do then do they sin? Are they in the same test as we and jins are? If they have freewill and they do not sin because they are in presence (hazoori) of God all the time, then Iblis has the same "hazoori", he sinned, as he was jin and had free will.
It is evident from the Qur'an that angels do have their own free will and you are right they do not sin because they remain in God's presence most of the time. As for Iblees and other jinn they are not in the presence of God. It was only at the time of creation that he the other jinn had been called to be there for a purpose.