I have 2009 civic lx that was draining battery in 12 hours or lesw from a full charge so I removed tne negiaive battery cable and hooked a test light between the terminal and cable and it stayed lit till I pulled the compressor clutch fuse then it went out and now battery is staying charged, how can I tell if the clutch is bad or the relay is bad?

 

That would almost have to be the relay. There's usually another relay in the relay box of the same type (for the rear defog grid, etc) which you can swap in as a test.