Impure and flammable refrigerants are a real and present danger today-an unpleasant consequence of the phaseout of R-12. At the very least, technicians must use extra caution when servicing air conditioners on unfamiliar vehicles. Plus, the situation may warrant investing in a refrigerant purity tester. Most vehicle air conditioners on the road still use R-12 refrigerant. The skyrocketing cost and sporadic shortages of R-12 have spurred use of tainted R-12 or troublesome alternative refrigerants.
For example, R-22 is a common commercial refrigerant. Highwaymen have duped both professional technicians and shade-tree mechanics by selling them containers of R-22 instead of R-12. What's more, blends of approximately 90 percent R-12 and 10 percent R-22 have been discovered.
Because R-22 operates at a higher pressure than R-12, it won't work well in an automotive application. Even 10 percent R-22 raises system pressure enough to hurt cooling performance. And pity the poor tech who doesn't realize the fresh refrigerant he installed is impure: The system doesn't cool adequately, system pressures are abnormally high and he can't find any obvious reason why!
Plus, sources said some retailers have cans of R-22 on their store shelves. Although fine print on the can identifies it as non-automotive refrigerant, backyard mechanics are still installing it in vehicle air conditioners, they said.
Should a technician draw R-22 or an R-12/R-22 blend into his recycler, he has no choice but to scrap the contents of the refrigerant container. (For information on proper disposal, contact your refrigerant supplier.)
Another threat is non-automotive R-12. Reportedly, some people are using automotive recyclers to pilfer R-12 from old refrigerators. However, experts told TIRE BUSINESS that a compressor failure in a refrigerator may make the R-12 highly acidic.
And since automotive refrigerant recyclers are not designed to treat this problem, an unwary service technician could charge a customer's car with this impure refrigerant.
According to Ward Atkinson, an air conditioning engineer at Sun Test Engineering in Scottsdale, Ariz., acidic R-12 would immediately attack and corrode metal parts of the air conditioner.
To make matters worse, flammable blends of propane- and butane-type refrigerants have come on the market.
Consequently, air conditioning service experts urge technicians to exercise extra care-especially with unfamiliar vehicles. First, get as accurate a vehicle history as possible from the customer. If the air conditioner was repaired, try to verify who worked on it.
Second, watch for identification decals or tags indicating the air conditioner has an alternative refrigerant in it.
Third, be alert for unfamiliar odors coming from the air conditioner.
Fourth, never use an open flame-type leak detector until you are certain which refrigerant the system has inside it.
Fifth, don't risk contaminating a recycler with an unknown refrigerant. Instead, empty the refrigerant into a DOT-certified container with a shut-off valve for proper disposal. Use a vacuum pump to lower the container's pressure to at least 28 inches/Hg. Connect the container to the vehicle's refrigeration system, open its shut-off valve and collect the unknown refrigerant.
Veteran air conditioning specialist Tom Banghart of Banghart Distributors in Havertown, Pa., recommended chilling the container in dry ice ahead of time. Prechilling speeds the purging process by increasing the pressure differential between the empty container and the vehicle's refrigeration system, he said.
A purity tester enables service personnel to flag impure or unknown refrigerants in vehicle air conditioners or in containers. The typical tester is portable and requires only a one-hose hookup to the vehicle or container. Within about a minute or less, a tester readout or indicator issues its verdict.
The capabilities of refrigerant purity testers vary from make to make. For instance, some units check only R-12, others both R-12 and R-134a.
After analyzing the refrigerant, some purity testers display results such as ``R-12,'' ``R-134a,'' or ``Unknown.'' But as of presstime, at least one unit provides considerably more information. Neutronics Inc. of Exton, Pa., makes a purity tester that also gives visual and audible warnings when it sniffs flammable refrigerants. The tester's audible alarm sounds and a graphic symbol of a flame on the tester panel illuminates.
According to Neutronics spokesman Gary Halpern, the tester is also the only one on the market that actually identifies the percentage of impurity in the refrigerant to an accuracy of 0.1 percent. This is useful for post-conversion quality checks on air conditioners that have been converted from R-12 to R-134a. To ensure consistent cooling performance on these ``conversions,'' the Society of Automotive Engineers (SAE) has set limits for the amount of hydrocarbons lingering inside the system, he said.
What's more, sources said the SAE probably will issue purity standards for refrigerant very soon.
Besides hydrocarbon-type contaminants, excessive air in refrigerant hampers cooling performance, too. Tire dealers who have refrigerant recyclers know there's a procedure for properly venting excessive air from refrigerant containers. Mr. Halpern said Neutronics' purity tester also stands out by accurately measuring the amount of air inside a refrigerant container or system.
If a careless technician hasn't vented a container of recycled refrigerant properly, instituting routine quality checks with a purity tester will catch the mistake before the refrigerant ends up in a vehicle's air conditioner, he said.