This is one of the A/C lines right?

I changed out all the fluids in my 2004 over the weekend, finally got the skid plates off, and found this super rusty line (circled in red) the rust looks worse then it actually is due to the lighting, but it is still badly rusted.

If it is a A/C line is that the high or low pressure, and if it isnt, what is it?

 

no, all you hade to do was simply follow the lines.

those are your power steering lines from and back to the pump.

if its rusty you might want to replace it before it starts leaking on you.