Automotive engineers are developing new vehicle technologies at a rapid pace. Just as rapidly, legislators are adopting new laws that have a dramatic effect on the automotive service profession. As we step further and further away from the basic automotive systems of the past, these technological strides bring with them a significant burden of increased complexity and the responsibility to repair vehicles properly and efficiently when they fail.
One of the automotive systems at the forefront of this technological revolution is the climate control system. What was once a basic system designed to heat and cool the interior of a vehicle has evolved into computer controlled, multi-zone, automatic temperature control system with cabin air filtration.
No longer are a few tools and some basic training adequate to diagnose and service modern climate control systems. Without proper tools and up-to-date training, technician mistakes are inevitable.
Are you equipped with both the tools and the training to handle today’s ever more complex climate control systems? Below are the 10 most common mistakes made when servicing climate control systems. Recognize any of them?
1. Not Identifying System Refrigerant
The EPA SNAP (Significant New Alternatives Policy) lists over a dozen refrigerants “approved” for automotive use. Some of these alternatives are hydrocarbon (propane and butane) blends that are highly flammable. These refrigerants, however, are tested only for their environmental impact and their threat to human safety, not for how well they work in an automotive system. No manufacturer approves the use of any refrigerant other than what the vehicle came with. But do you think that will stop everyone from trying anyway?
The only way of knowing what is in an A/C system, storage cylinder or container is to use a refrigerant identifier. Owning one also helps you to avoid damage to your service equipment from contaminated refrigerant and prevents contamination of the shop’s 134a supply, warranty loss on recovery equipment, lost service profits and even risk of injury.
“Refrigerant contamination is one of the biggest issues confronting our industry. The increasing cost of A/C service, the lack of federal guidelines, and increasing DIY usage has opened the door to a variety of refrigerant substitutes that are not only potentially harmful to shops, but to the technicians as well,” says Peter Coll, Refrigerant Analysis Division Manager, Neutronics Inc. “Today, you can’t afford to guess at the quality of refrigerant in the cars you service. You need to know exactly what’s in that A/C system before you work on it.”
2. Not Using the Correct, OEM Specified Lubricant
The manufacturer of the vehicle or compressor determines viscosity and lubricant type. Some lubricant suppliers claim their oils are universal and can be used for every application but are you willing to stake your reputation on it?
If CFC-12 is the refrigerant, mineral oil is specified. If the vehicle has been retrofitted for use with HFC-134a, then Ester oil is used. If the vehicle was originally equipped with HFC-134a, an OEM specified viscosity PAG (polyalkaline glycol) lubricant is required.
In general, four viscosities of PAG oil are offered with the smaller number indicating less viscous oil. The 46-centistoke lubricant is used on many Nippon-Denso style compressors. This includes many of the Ford and Chrysler compressors. The 100-centistoke lubricant is used on several import and aftermarket compressors. The 125-centistoke is a special lubricant for the OEM Delphi-Harrison V5. General Motors determined that when the OEM V5 compressor is retrofitted, the system requires a specially formulated PAG lubricant. The 150-centistoke lubricant is used primarily on the Delphi-Harrison (General Motors) compressors.
Climate Protection Pledge The Climate Protection Pledge is a pilot program under the Strategic Climate Projects, Climate Protection Partnerships Division of the U.S. EPA. HFC-134a, the refrigerant used in most automotive and light truck air conditioners on the road today, is recognized as a potent greenhouse gas. The mobile air conditioning industry has been working on system designs, service equipment, tools and procedures to reduce refrigerant leaks. The voluntary Climate Protection Pledge program is designed to recognize those automotive service shops that use tools, equipment and best practices to reduce refrigerant emissions. Consumers, even in the midst of the current recession, are concerned about the environment, and respond favorably to companies and service providers who demonstrate that they are environmentally responsible. By taking the Climate Protection Pledge, automotive air conditioning service facilities can do the right thing and get recognition for it. In order to take the pledge, shops must be properly equipped, including on-site use of the latest generation of refrigerant recovery/recycling/recharging equipment. That equipment, which must be certified to SAE International standard J2788, must recovery at least 95 percent of the refrigerant from an air conditioning system, and recharge the system with the proper amount of refrigerant. Another important component of the pledge is technician training, and shops taking the pledge are encouraged to have all of their A/C technicians complete a self-study training program focusing on best practices for leak detection, service and repair, equipment maintenance and refrigerant conservation. These practices are designed to promote shop savings and efficiency, consumer satisfaction and environmental protection. Shops taking the pledge must agree not to promote “top-off” or recharge of leaking A/C systems without first repairing leaks, and must agree to explain the potential A/C system and environmental benefits of having refrigerant leaks repaired. Shops also must set continuous improvement goals which may include upgrading equipment and tools, training additional technicians in best service practices, implementing tool and equipment maintenance programs or other similar goals. The U.S. EPA will recognize shops that meet the criteria for having taken the Climate Protection Pledge with certificates and other promotional items. For more information and to take the Climate Protection Pledge, go to www.macsw.org. |
3. Improperly Recharging Systems
The basic principles of automotive air conditioning have not changed; what has changed is the quantity of refrigerant needed to get the job done.
Early systems required large quantities of refrigerant — three pounds or more were not uncommon. Charge tolerances were rather wide because of the large amount of refrigerant in these systems. A simple digital scale and charging station could easily handle the service.
Today, most passenger cars and light duty trucks carry less than 20 ounces of refrigerant; just barely over one pound. One of the smallest capacity systems on the market is the Toyota Yaris, which runs on approximately 11 ounces. With the accuracy of some older scales at ± 0.2 pound, or more than three ounces, the possibility of over- or under-charging a system is a definite possibility.
Just two ounces of over/under charging will reduce performance, and two ounces of under-charging will affect compressor lubrication. For greater accuracy, a charging station certified to SAE International standard J2788 is the preferred method of charging.
4. Not Using Correct, OEM Approved Refrigerants
At present, there are only two OEM recommended refrigerants: CFC12 and HFC134a. CFC-12 is approved for use in vehicles manufactured prior to the changeover to HFC-134a, while HFC-134a is the only refrigerant approved for use by automakers as a retrofit refrigerant for CFC-12 vehicles. Vehicle manufacturers have approved HFC134a for use in vehicles from 1992 and later. Current HFC-134a mobile A/C systems are designed and tested only for use with HFC-134a refrigerant and the specific PAG lubricant.
Even though there are a number of other refrigerants on the market listed by the EPA as environmentally acceptable, only CFC12 and HFC134a are OEM approved for use.
5. Not Replacing Components with Ones That Match OEM Performance
In many cases when servicing an air conditioning system, replacement parts are expensive and the technician might be inclined to save money by purchasing aftermarket parts. But beware: Not all aftermarket parts are created equally!
We all know that as refrigerant cycles through the air conditioning system, it is supposed to evaporate in the evaporator and absorb heat in the process. Afterwards, it condenses in the condenser to give up the heat that it absorbed in the evaporator coil.
If either of these heat exchangers, in addition to the third heat exchanger (the radiator), does not match OEM specifications for performance, the system will not operate at peak efficiency and you will face a comeback.
A part might look the same as the original and bolt in place correctly, but that does not mean it meets OEM performance. Stick with OEM or aftermarket names you can trust, check the specs, and avoid the comeback.
6. Not Performing a Thorough System Evacuation
According to a Mobile Air Conditioning Society (MACS) report, depending on the ambient temperature, many older recovery/recycling machines in operation today may recover only 50 percent of the refrigerant from a system. Even the best machines that far exceed the requirements old SAE J2210 standard may leave up to 30 percent refrigerant behind.
For example: In a system with a 16-ounce capacity and 12 ounces remaining in the system, you unknowingly recover only half the charge. That leaves six ounces of refrigerant remaining in the system. When you recharge the system with 15 ounces of fresh refrigerant, the system will have 21 ounces and be overcharged by a staggering 38 percent.
If you have purchased a recovery/recycle machine that conforms to the newer SAE J2788 standard, you are guaranteed a straightforward recovery performance of 95 percent. If you're still using an older machine, make sure the vacuum pump is healthy and you allow the system to sit for 5-10 minutes after a recovery to allow any remaining charge to show itself (pressure gauges increase above zero). You may have to repeat the process of recover/sit/recover a few times to get it all out.
Remember, it is against federal law to release any refrigerant directly to the atmosphere, regardless of the reason.
7. Not Properly and Regularly Maintaining A/C System Service Equipment
Refrigerant recovery and recycling machines have come a long way from their simple beginnings. However, as the machines have become more complex, there is more to go wrong.
Surprisingly, basic maintenance on today’s complex recycle/recovery machines has not changed that much. They still need to have the filters changed regularly and have the vacuum pump oil changed. Purging the air from the storage tank is a common maintenance item often forgotten. Daily maintenance items, such as draining the refrigerant oil recovery bottle after each use, also are required.
Changing the filters, O-rings, oils and leak-checking the unit usually can be done in about one to one and a half hours with the parts costing less than $100. Some machines will prompt the user and tell them that it is time for maintenance, while others may make use of an hour meter to indicate when maintenance is due.
Broken service equipment costs you money, both in lost productivity and actual repair costs. With repair bills for recovery/recycling machines averaging $400 and higher, and the cost of a new RRR machine averaging $2,500 plus, you can see why maintenance is the answer.
8. Improperly Flushing the System
When a compressor has a catastrophic failure, debris can be spread throughout the refrigerant loop. Flushing to remove debris that could cause failure of the replacement compressor and to remove debris that could impede refrigerant flow through the condenser is only a natural. But flush with the wrong product or use the wrong procedure and you could do more harm than good.
Once again, this is the time to follow either the OEM or aftermarket parts manufacturer’s recommendations. And their recommendations vary considerably. General Motors recommends flushing with liquid refrigerant, while Ford recommends a liquid flushing solvent. Both manufacturers also recommend a closed loop flushing machine be used. Due to the multiple flow paths in most modern heat exchangers, many manufacturers favor replacement over flushing for the proper repair of their systems.
9. Not Verifying Repairs
There is nothing worse than seeing a vehicle you recently repaired come back into your shop with the same complaint. Because most failures in an A/C system are not the result of a manufacturer’s defect, it is extremely important to not only identify the root cause of the failure, but also to verify the repair has corrected the underlying problem.
When a customer arrives at your door with an A/C complaint, the first and most important diagnostic tool most shops use is to conduct an in-depth question and answer session with the customer and carefully listen to their description of the problem. So when the repairs are completed, take the time to perform a quality check against the customer’s complaint.
10. Not Keeping Current with Service Information and Education
There is no doubt that a strong foundation in the basics of automotive repair, combined with hands-on experience, plays a major part in a technician's education. However, all but the most basic automotive diagnosis today requires detailed, product-specific training.
Each year, technicians make considerable investments in tools and the “palaces on wheels” to hold them. Yet, in the end, tools alone cannot fix the vehicle. Knowledge and the tenacity to find answers to problems efficiently are what define the modern day technician.
Keeping the shop’s service information system updated and taking time to update your technician’s training allows for a more efficient workflow and greater profitability.
