The systems have minor differences, but in most ways they're the same. If
the stuff your friend added had sealer in it, that could be bad. How the
sealer works is that it seals when it comes in contact with moisture. If
there's any moisture in the system, it could clog the system. So, if
that's the case, perhaps it's best he doesn't show them the can.
The dealer isn't allowed to charge your friend to recharge the system and
charge Hyundai to repair the system. If the system is defective and
covered by warranty, then Hyundai will pay the dealer for the repair work,
including the diagnosis, the refrigerant, and the associated labor to
evacuate and recharge. Most dealers, however, will quote 1hr labor to
check and diagnose, because if they can't find a leak, Hyundai won't pay
them for any work they've done. If they check the system and find a
warrantable problem, they should then not charge the $96.
I agree he should probably wait until it has an issue. I would also
recommend not attempting recharge yourself until you're outside the