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Rudi Kiefer: Crank up the AC, but also check to see if your unit is due for an upgrade
Rudi Kiefer
You’re not alone this week in checking the thermostat and cranking the air conditioning up by a notch or two. If your home system says “Carrier” on it, you’re also celebrating the inventor who made it all possible.

The invention by Willis Carrier, a.k.a. “the Father of Air Conditioning,” wasn’t really aiming at reducing room temperatures back in 1903. He invented a giant dehumidifier, with the purpose of removing moisture from the air.

The printing industry had been plagued by the fact that paper is made from wood, which expands and contracts with the rise and fall of humidity. Carrier’s invention involved coils containing cold water with air passing through. Condensation on the cold surfaces turned water vapor (the humidity content of the air) into liquid water, which could then be drained away.

Modern refrigerated air conditioning, used in most of the humid eastern half of the U.S., reduces room temperature as well as humidity. For that purpose, the coils are filled with a refrigerant gas instead of water. It’s generally referred to as Freon, although regulations and chemistry have been changing significantly during the last decade.

If you were a car owner in the 1980s and ’90s, you’ll remember the small cans of R-12 refrigerant available for one dollar at K-Mart and elsewhere. I had to recharge the air conditioning in my ’86 Oldsmobile once a year because there was always a slow leak. Home units from the ’90s and early 2000s contain R-22 (chlorodifluoromethane), similar in some ways to R-12. But both are hydrochlorofluorocarbons, harmful to the atmosphere as well as to efforts at pronouncing their names. Older cars had to be converted to the newer R-134a, which could be a costly procedure.

Home air conditioning systems using R-22 are now approaching the end of their life span. Equipment installed in the early 2000s has a life span of 10 to 12 years, according to my local service expert, and regulations have been phasing out R-22 since 2010.

If an old R-22 air conditioner is losing Freon and putting out lukewarm air, it may not be worth the cost of recharging because its mechanical end is coming soon. The air compressor doing the hard work inside it is probably wearing out, and a new unit with the more environmentally friendly refrigerant will cool the house again nicely.

Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at