Why is the SEER rating on the Energy Guide different than what my dealer quoted?

Each split system cooling unit has a nominal SEER rating. This rating can be increased with the upgrade of the same series indoor unit. The SEER rating of a system is derived based on the combination of equipment installed in the home. The outdoor equipment (heat pump or air conditioner), as well as the indoor equipment (evaporator coil and furnace, or air handler), play a vital role in the total rating.