The small screen is an "Oriphis tube" it is in the tube that runs from you're reciever/drier into the tube that goes to the e-coil (evaporator coil) you'll need a tool like a fuel line disconnect tool to undo this. They can really be a pain in the *** to get out. It catch's debri in the system.

If it isn't replaced the warranty usually is voided on the compressor.