Its usually in the model number, Without looking it up I would say its 2.5 ton. The 030
Mine is 10 seer and 16 years old with a leak in the coil. Tech told me I was probably getting 2 seer from it and I believe it since last month's electric bill was $250 and it wasn't all that cold!SEER is rated by AHRI and is listed in the performance tables of York and AHRI.
As the unit ages and the compressor wears it loses efficiency so it was 11 new, now it is less.