Where is low-side-port on 97 escort?

While I'm not certainly exactly where it is on this model, I can tell you how to find it. Locate your AC compressor. There are two hoses going into it - one has a significantly larger diameter than the other. Trace that line back until you find the schrader valve - it'll usually be capped off with a black plastic cap. You'll know it's the right one because it's the one your AC recharge kit will fit onto snugly - the high and low side schrader valves are different diameters.