There is a good chance it is a leaking condenser as that has happened to a lot of 2018's. You are past the 36K warranty and that would be a >$1,000 repair. If the refrigerant is low and they can't find a leak they may try and just sell you a refrigerant replacement but that is expensive and will likely only solve the problem temporarily as there is no reason to lose all of the refrigerant in three years. If they locate a leak in the condenser you can ask the dealer if there is no visible damage to the condenser (like from a rock etc.) can they request Honda to replace the condenser under warranty since you are only a few thousand miles past the warranty, and mention that condenser leaks seem to be common on the 2018's. If the answer comes back no, you could offer to pay for the labor if Honda will pay for the part and they may accept that.My Clarity started blowing warm air and I plan to take it to the dealer. 44k miles; no previous dealer service.
Anything obvious to get done while there? I know there was a software fix for the range overcalculation and I think there's a fix for the charging circuit being fussy with some commercial L2 chargers.