The last thing on your mind may be your home’s air conditioning unit, but, a new law goes into effect at the end of the year that could leave you sweltering next summer if you don’t pay attention.

Freon can still be used to service existing air conditioners while supplies of the coolant last.  Most air conditioning units manufactured before 2010 use Freon, or R-22.  Most manufactured after that do not.  They use other coolants that are not banned.

The EPA states, “people can continue to use air conditioning equipment that uses R-22, whether it is a window unit or a central cooling system, and they are not required to replace their existing equipment.”

“It’s very, very expensive. It’s almost like gold, and they’ve done that to try to encourage people to upgrade and not just keep going along with the old. It is very price prohibitive now,”  said Scott MacFarlane, owner of Dedham-based MacFarlane Energy.

MacFarlane said he carries a limited supply of Freon in his trucks.  He suggests anyone who has had a leak in a unit may want to start planning and budgeting to upgrade their air conditioner.

“When they come to next July and all of a sudden their unit dies, and we have to replace a whole unit, and everybody’s busy, they will have to wait 2-to-3 weeks to get the unit fixed because we’re busy trying to upgrade other people’s equipment. So, it’s always better to be proactive and do it ahead of time if you can afford to do it,”  MacFarlane said.

But if your air conditioning unit was built prior to 2010, and there’s no leak and has been properly maintained, like Gerry Chisholm’s, experts say there’s no need to replace it now.

HVAC experts also say if you have an old window air conditioner and it leaks, it’s likely cheaper to buy a new one, rather than repair it.  Also, changes with Freon won’t effect your vehicle since a different refrigerant is used in cars, trucks and SUVs.