Rheem RPLB-030JAZ - is it a Heat Pump or AC unit?
Rheem's own website does seem remarkably unhelpful in suporting your equipment. Searching for RPLB there turns up no results...a sad effort indeed. You should contact them and request information and a manual, and perhaps vent a bit about the website not admitting your product exists.

This document from NYC.gov does suggest that what you have is probably a 30K btu/hr heat pump, though it only gets as specific as 

RPLB 030* and * leads to a note of "with suffixes"

Do you have an "inside unit"? if so, look for an access cover on that, which may have your manual stuck inside it (possibly in an envelope taped to the inside of the panel.)