Won't cool.only drawing 4 amps when compressor

I would remove the lid from the compressor and verify the connections are all in place and not rusted or melted, More then likely your capacitor has gone bad for your compressor, unless you have the proper testing meter then Id recommend replacing the capacitor, and just check for any loose or burnt wires.
Take it with you to a local Hvac supplier to get a proper replacement.

Good Luck!