If you're having trouble, I'd suggest the following:
1. If you're not a healer, use your healing companion. There's damage throughout the fight, and it's a long fight so it can add up.
2. Ignore the generators. I've beat the fight 3 times out of 4 attempts, and the only time I died was when I shut down the generators. They're an unnecessary distraction.
3. Don't forget your heroic moment. and other cooldowns.
4. Don't rush. As long as you don't stand in the bad, Archon does damage very slowly. Your mission is simply to deal damage to him faster than he does to you or your companion, and that's not difficult as long as you're patient.