Hi, I assume the RV owner has no manual for his Carrier unit or you would not be asking for assistance. You did not mention a model number for the Carrier unit but perhaps the attached manual link will match. The only reference to trouble codes is on page 2-4 but I did not see 7 flashes listed (did not read in much detail though).....only up to 6 so perhaps this manual is of little or no value for you.
https://manuals.heartlandowners.org/...ice_Manual.pdf