there are 9 SL berths in each coach. This means 18 people can be accommodated in one coach. For 14 coach it is 14 * 18 = 252.
So RAC 238 is justified because all SL berths are not booked for RAC the difference 252 - 238 = 14 means 7 SL berths are allotted for TTE and RPF personals for security reason