First, find the full path to the psql binary, by running "which psql" . Then run "ldd /path/to/psql" . For example, if the psql binary is /usr/local/bin/psql , run "ldd /usr/local/bin/psql" .
Then look at the list of libraries it is linking against. I believe you will find that it is linked against an SSL library that is not on the machine.