Top Stories Headline News
	Contents This Issue's Index
	Editorials Editorials Columns Letters
	Arts & Leisure Reviews & Schedules
	Outdoors Fishing/Hunting Outdoor Magazine
	Sports Local Scores & Standings
	Food Recipes for culinary delights
	Bridges Bridges of the Upper Delaware
	Back Issues
	Search
	Links
	Commerce Sponsors
	Classified Ads Find it here
	Staff Pages
	Masthead
	Design Studio
	Subscriptions Get your copy delivered

Retrofitting your car’s A/C

If you own a car that is a 1993 or older, its air conditioning (A/C) system is designed to use the R-12 refrigerant, commonly known as Freon. Since 1994, all vehicles made with an air conditioning system are designed to use a different type of refrigerant, known as R-134a. R-134a is supposedly not harmful to the atmosphere and does not deplete the ozone layer as R-12 does.

There are some differences between the two systems. A/C systems that use the R-134 refrigerant are designed to run at higher pressures — so the R-134a is not compatible with the R-12. You can’t just add some R-134a into your A/C system. You either have to convert the system to use R-134 or continue using R-12. R-12 is probably the easiest way to go, but there are some major disadvantages.

First, the R-12 manufacturers have stopped making it years ago, so what is currently available is very expensive. And the remaining R-12 stocks will be depleted in the foreseeable future.

If your 1993 or older vehicle’s system works fine, then there’s nothing to worry about. However, there might come a time when the system will need recharging and perhaps parts replacement. It might be better, in the long run, to retrofit your system to work with R-134a.

Originally, it was thought that major components would have to be changed in order for the A/C system to become compatible with R-134. However, as more research was done, this rumor was proven erroneous. If an R-12 system is working OK, components do not have to be changed and the R-12 can be replaced with R-134a without opening up the system. Hoses and O-rings (if not damaged) do not need to be replaced because the mineral oil used in the R-12 system is absorbed by the rubber and actually forms a protective barrier, protecting it from the R-134a.

Probably the simplest and most cost-effective retrofitting kit available is the one made by Interdynamics, Inc. (80 39th Street, Brooklyn, NY 11232; 718/499-0608). What makes this kit different is that the A/C system does not need to be opened or flushed to be changed over to use R-134a. The process is rather simple. First, the old R-12 must be completely evacuated from the system. This is something that has to be done by a certified mechanic using R-12 evacuation equipment. The evacuated R-12, however, is quite valuable, so the cost of this process shouldn’t be much.

After the R-12 is evacuated, the service port adapters and caps that come with the kit must be installed so that the system can accept the R-134a. The kit also comes with a charging hose, ester oil (which is compatible with both Ford and GM systems) and two cans of R-134a refrigerant. If your system needs more refrigerant, you can get it at any auto parts store. With the exception of the evacuation procedure, all of this is easily within the capabilities of the backyard mechanic. Or you can have a mechanic do it for you.

The question that most often arises is that factory R-134a systems are designed to work at higher pressures than the R-12 systems were designed to. To get around this problem, only 80-85 percent of the original charge amount is replaced with R-134a. This may or may not affect the system’s output temperature. Interdynamics reports that some cars actually produce colder air, while most will put out the same temperature as before. On some other vehicles (rear wheel drive domestic vehicles) the duct temperature may be two-to-four degrees warmer. Duct temperature is typically in the 36-38 degree range, so the two to four degree increase is really quite negligible. This is based on Interdynamic’s experience with the hundreds of thousands of kits they have sold since 1997.

The nicest part about this kit, perhaps, is that it is very reasonably priced. The J.C. Whitney catalog has the kit listing for $29.95 and although it’ll probably cost a few dollars more, it can be had at most local auto part stores and chains.

[Peter C. Sessler is the author of 25 books on cars, published by Motorbooks International, Tab Books, Smithmark Publishers, and HP Books. Some of his titles include "Ford Pickup Red Book," "Muscle Car Greats," and "Car Collector’s Handbook." Publication is pending on his latest book, "Model Car Handbook," to be published by Scale Sports.]