Can't keep R134a in the system, only last for a few hours. What might cause this

Your A/C system has a few hoses, compressor, hard lines, fittings, condenser, and evaporator core. Unfortunately the Freon is colorless and the best way to confirm the leak is to add or have a shop add dye to the system to properly locate the leak. With your leak as bad as it sounds it should be quite easy to locate.