Discovered miss matched system, undersized for the home, with defective coil leaking 410A refrigerant. Supply Plenum has been hacked up and modified improperly, causing deficient airflow to at least half of the home. One Guard authorization technician advised that these issues are not covered, due to type and cause of failure. Replacing defective coil and modifying ducts is a minor improvement, but is not a sufficient option for reliable and lasting home comfort. Heat load calculation and duct sizing calls for a properly matched 5 ton system, for proper and effective cooling of the home.