If your diagnosing an electrical problem, and need to locate components in the electrical system it's best to have a wiring diagram. There are likely many relays in this car so you want to make sure you replace the correct one.
Find a diagram here: http://bit.ly/mitchell_repair_manuals_online
I have a 2004 Vibe, and the AC Light comes on and the engine sounds different but, the Clutch on the Compressor is not engaging. I was told I need a new condensor because the clutch is part of it and does not come separately.