I must assume that you are using "read from file" to fill the load limits for the directions A, B & C. I will guess you are using the API610 data. This data is held in the SYSTEM in the file API-610.eql. That file defines the translation from the API 610 coordinates x,y,z to the CAESAR II coordinates A,B,C for each of the three nozzle orientations - Top, Side & End.
For Top nozzles: B is shaft orientation
For Side and End nozzles: B is up

I am uncertain of your sign issue. But signs are not significant in this evaluation. The check is on the magnitude (i.e., using the absolute value) and there is no nozzle combination check (as in API 610 Annex F).