What is SEER?
SEER is an abbreviation for Seasonal Energy Efficiency Rating. It is the most commonly used measure of the efficiency of consumer central air conditioning systems. (EER or Energy Efficiency Rating is the most commonly used measure of efficiency for commericial air conditioning systems.)

What is EER?

EER is an abbreviation for Energy Efficiency Rating. The Air-Conditioning and Refrigeration Institute standardized this rating, which reports central air conditioning efficiency at 80 degrees F indoors and 95 degrees F outdoors. This rating measures steady-state efficiency -- that is, the efficiency of the air conditioner once it is up and running.