Had service call to high eff. rheem unit - not sure how high the eff. is, but found bad condenser fan motor.
Original motor was 1/16th H.P.( .45amps ), can you believe it. Two blade fan. Local Rhem supplier did not even have this motor, had to go back with 1/5 HP.
This is one way to get eff rating. Undersize outdoor unit fan motor. Unit less than 6 yrs old
This is one of the reasons I don't trust high eff. equipment. What are the manufacturers going to do to get 13+ seer ratings next year.
Also have seen units whose reversing valve would energize & deenergize by the thermostat ( not the heat-off-cool switch ). Found out that that was to get higher eff. rating. Less energy usage if reversing valve was not kept energized in cooling cycle.
What other ways do manufacturers have to 'cheat' on eff. rating ??