Can you send the serial number again, but this time put spaces between the numbers. Our system did not recognize it.
The 12 amps just mean that the unit is rated up to 12 amps.
The unit was produced in December of 1991 according to the serial number. I am trying to find the energy ratings but can find nothing, but I can tell you why it is not considered energy efficient. First, it is the refrigerant that is being used, which is most likely R12 on this unit. This freon and the associated compressor does not run efficiently. Secondly, this uses a mechanical thermostat to measure temperature. These are not as accurate as electronic thermistors and can keep the unit running longer to maintain temperature. lastly, the defrost is a operated by a mechanical timer. These timers place the unit in a defrost every 8 hours. This turns a heater on to melt the frost. The heater draws a lot of power and then you need to cool the unit back down. Today's refrigerators use adaptive defrost controls that sense whether or not the machine needs to defrost. This cuts down on the defrost cycles.
With all of that being said, if your unit is not broken, don't fix i. These are solid refrigerators and you will not by anything as reliable as these anymore. The new ones are energy efficient, but not as reliable as the old ones.