Is it an R-134a or R-1234y system?
Most of the posts here indicate the rasping sound from the evaporator is from the system being low. Not the evaporator leaking. So you have a leak, but why have you concluded its a leak in the evaporator? Cause from the posts I read the noise comes from the system being low, not a leak in the evaporator itself. You're leak could be somewhere else that is much easier and cheaper to fix.
It's R-1234YF. If it wasn't I would have done it myself or taken it to a local shop for diagnostic and repair, which I actually did before taking it to the dealer. They returned it to me no charge and suggested I take it to the dealer because either way they don't fill 1234YF. I took it to the dealer. They said it was low, did a system evac and replaced a hose that looked like a potential culprit. They re-filled the system and tested it. All good. I got it back and after about two weeks it came back. Sometimes it cools, sometimes it blows just air, but the rasping it continuous. The hotter it is outside the longer it takes to actually blow cold air if any at all in the dead of summer. The dealer guarantees a repair for up to 24 months, but I imagine they are going to have to do another evac and refill to find out where it's potentially leaking again. If it was 134-a I wouldn't hesitate, it's cheap. But the 1234YF is just ridiculously priced to fill.
From what I have researched, a lot of people have found damaged cores (after eliminating other options) which doesn't make sense considering they are up against the firewall.
