Does efficiency fall off if it’s never recharged/serviced?
No. Your old unit will be charged with R 12. A very stable chemical.
So stable that it drifts all the way up to the ozone layer and .......
All of this advise comes without me knowing anything about what you have installed so take it for what it's worth.
Now. if you are worried about reduced efficiency, there are a couple of things that you can do.
RE: So my 2005 air conditioners and refrigeration is 21 years old.
It sounds like you have one condensing unit for AC and your refrigeration. I doubt that so, I will go with two units.
If the units are air cooled, cleaning the condenser fins and fan blade will keep the unit and the refrigerant cooler and give you better efficiency.
Even a small build up of crud on the leading edge of the fan can cut down the airflow significantly.
Same with dust, fluff and crud in the condenser fins.
Also, check that there is nothing even partially blocking the airflow into, around and out of the unit.
If the units are water cooled, ensure that there is good flow through the condenser.
For your refrigerator, seals have a life and if they get weak, flattered, come unstuck or broken you will loose a lot of efficiency, so check your seals.
For your AC units. As with the air cooled condenser, cleaning the evaporator fins and fan blade will increase airflow into the cabin and heat transfer, giving you better efficiency. Even and small build up of crud on the leading edge can cut down the airflow significantly.Your AC unit should have filters.
Wash filters in soapy water to remove dust and oil, If they fall apart as you are washing them , well, get new ones.
gary
