If he opens the system and it's the strainer, I'd have to foot the bill for labor and parts (new strainer and filter). If the strainer is not clogged, he'll bring in new evaporator coil from the manufacturer (in warranty). All this is dandy, but fails to address quality of their work. In my mind, if the evaporator failed due to manufacturer's defect, that's one thing, but if either strainer or evaporator got clogged due to solder getting loose (often invoked, albeit brazed joints were used) or corrosion due to humidity, or mixed oils, etc., to me that sounds like an installation issue, and their reputation should be on the line. Thus far, they regarded loose solder as an act of God, that is nobody's fault.