Installation and modification of A/C systems for US and imported vehicles

By Ward Atkinson

Members have requested information regarding requirements that apply to vehicles produced by OEM vehicle manufacturers, commercial upfitters and independent A/C repair or service facilities that install or modify mobile A/C systems.
All A/C refrigerants listed as acceptable, including R-134a and R-1234yf, are subject to use conditions requiring labeling and the use of unique fittings. EPA is requiring the same use conditions for R-1234yf in newly manufactured medium duty passenger vehicles, HD pickup trucks and complete HD vans as it mandates in newly manufactured cars and light duty trucks.

A/C systems designed to use R-1234yf must meet the requirements of SAE J639, Safety Standards for Motor Vehicle Refrigerant Vapor Compression Systems. This document sets safety standards that include unique fittings; a warning label indicating the refrigerant’s identity and notification that it is a mildly flammable refrigerant (class A2L); and requirements for engineering design strategies that include a high-pressure compressor cutoff switch and location of pressure relief devices.

Designing the refrigerant circuit and connections to avoid refrigerant seeping into the passenger cabin ensures it is unlikely to enter the passenger cabin if there is a leak. Keeping refrigerant out of the passenger cabin minimizes the possibility there would be sufficient levels of refrigerant to reach flammable concentrations or hydrogen fluoride (HF) would be formed and transported where passengers might be exposed.

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Leaks under vacuum

By Steve Schaeber

A s OEMs continue improving their systems, technicians are seeing leaks more often attributed to the valve core located down inside the service port fitting, either on the high or low side of the system. Most of these leaks are discovered while the system is charged and under pressure, but that’s not the only time they can be found.
We recently worked on an F-650 bucket ……



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Tariffs a threat to auto repair industry

July 6, 2018 (Lansdale, PA) Today, 25 percent tariffs went into effect on a list of Chinese goods, and many MACS members have voiced concerns about the impact the tariffs will have on all sectors of our industry.

In the May issue of MACS ACtion™, Keith Leonard, MACS’ general counsel warned that tariffs were “a two-edged sword.”

On July 2, the Auto Care Association issued a press release detailing what it called the “unintended consequences that may ensue by imposing tariffs on imported autos and auto parts.” In its release the Auto Care Association cited an economic study by John Dunham and Associates, “which found that a 25 percent tariff on imported auto parts could cause a reduction of 17,800 jobs in the auto parts manufacturing sector, resulting in $1.4 billion in lost wages. The study further predicts that 6,800 jobs would be lost by vehicle repair shops and an additional 85,200 jobs in the auto care wholesale and retail segment due to lower demand. These are mostly small family-owned businesses that would suffer severe economic harm should a 25 percent tariff be levied on autos and auto parts.”

The complete Auto Care Association press release:

Since 1981, the Mobile Air Conditioning Society (MACS) Worldwide has been the advocate for service and repair owners, distributors, manufacturers and educators making their living in the total vehicle climate and thermal management industry.
MACS Worldwide empowers members to grow their businesses and delivers tangible member benefits through industry advocacy with government regulators and by providing accurate, unbiased training information, training products, training curriculum and money-saving affinity member services. MACS has assisted more than 1.2-million technicians to comply with the 1990 Clean Air Act requirements for certification in refrigerant recovery and recycling to protect the environment.

To learn more about MACS Worldwide visit our website at The MACS 2019 Training Event and Trade Show, A/Ccess will take place February 21-23 at the Anaheim Marriott in Anaheim, CA. A current calendar of all regional training can be found on the training page of MACS website at

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Spin-On Coolant Filters

By Chris Tyson, MACS Heavy Duty Contributor

While rarely seen in automotive and light truck systems, engine coolant filters (sometimes called water filters) can be found on many over-the-road, heavy duty truck and off-road engine cooling system applications. While most automotive engines average 12,000 to 15,000 miles per year, it’s common for some of these large trucks to reach 100,000 miles or more in the same time period. Combine such mileage with their much larger system capacities (some hold 15 gallons or more compared with around two for small cars), and it’s evident how important it can be to save maintenance time and money by filtering engine coolant on these large systems, rather than replacing it more frequently.

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The new world of HD and off-road equipment cooling

By Jerry Lemon, Lemco Mobile AC Consulting

Welcome to the new world of HD and off-road air conditioning. There was a time, not that long ago, when the HVAC system in a piece of heavy equipment, or an over-the-road (OTR) truck, was as simple as it could be made to be. Compressor, condenser, expansion valve, evaporator, and a drier or accumulator (sometimes both, really). Controls were equally simple – blower switch with a clutch post (that was the one labelled C), thermostat (with a probe into the coil – or in some cases, wrapped around the suction tube at the outlet of the evaporator), pressure switch (or switches – low, high and fan override, at most), and the compressor field coil. The simplest ones were connected in series with the single wire clutch grounding through the body of the compressor to complete the circuit. Others, such as Caterpillar, used a two-wire clutch and ground through the pressure switch and thermostat to complete the circuit. Regardless of the system in the not too distant past, they were simple enough to be drawn out on a single sheet of paper – both the mechanical and electrical sides. We used to laugh at the automotive service people with their vacuum controls, body control modules, multiple computer systems and everything else involved with A/C service.
Well, it has now come full circle to envelop all of us in the Off-Road and HD OTR air conditioning service industry. We are witness to fully blown, module controlled, HVAC with automatic climate control on demand (ATC – Automatic Temperature Control) built into the equipment at a factory level. The only difference is that now the automotive service guys are laughing at us. Why? Because they have the right to service the vehicles – which means that the manufacturers are required to make the diagnostics available for use. The HD OTR trucks and the Off-Road equipment manufacturers are not required to provide us with the necessary tools, and purchasing a suite of diagnostics that will enable us do these jobs run into the thousands of dollars, plus annual license fees. If we… to read more….CLICK HERE

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Are you ready for A/C season?

This is the MACS blog site if you are looking for the MACS main website click here.

Repair shops – one question: Are you prepared for A/C season 2018? Circle the right answer: YES – NO

What do you mean you don’t have a pen? How can we perform diagnostics without a pen? Remember the pen is an instrument of the plan! Ok, here we go.

However, before you  begin, I have a few more questions. Have your pen now?

  • Have we performed our annual A/C machine health check on our existing R/R/R machines?
  • Have we checked our scales, replaced the filters and replaced the compressor oil?
  • Have we calibrated our units?
  • If you purchased a first time Recovery/Recycle/Recharge machine have you checked all your fittings, filters, and tank for leaks? If you did purchase a new piece of A/C gear, did you send in the EPA certification documentation? See this link
  • Have we checked and/or updated our Section 609 technician certifications?
  • Now the really hard one, have you updated your current scan tools?
  • I can go on, but you catch my draft (no, it’s not a typo, I meant draft not drift.
    Read the rest of this article now.

Download the entire issue of MACS ACTION magazine.


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It’s not your Daddy’s Section 609 certification anymore

By Steve Schaeber, MACS Manager of Service Training

If you were Section 609 certified before 2015 and you’re scrambling to find your card to buy refrigerant this Spring that’s fine, but after you calm down and get a shiny new copy of your old 609 card, think about this…the first R-1234yf cars are coming out of warranty and may find their way into your service shop.
R-1234yf and the motor vehicle air conditioning (MVAC) systems using it are different from CFC-12 and HFC-134a systems. Vehicles using this refrigerant require different service procedures and shop equipment. A technician will need the skills to recognize the differences between refrigerants and how to service or repair each system properly and safely.
This chemical is NOT a “drop-in” refrigerant or one that should be used in other systems. Systems designed for R-1234yf should only be charged with that refrigerant. Systems designed for other refrigerants should only use those correct products.
Are you R-1234yf service ready? Do you have the proper equipment and do you know the proper service procedures?
MACS has been explaining the differences between working on R-134a cars and R-1234yf cars for the last five years and we find as we answer calls and hold training clinics that there are still people who refer to themselves as service professionals who have not received any training on R-1234yf mobile A/C systems.

The current MACS Section 609 program contains comprehensive training information on R-1234yf systems including best service practices and SAE J-standards, as well as specific safety procedures to protect you, your shop and your customer’s car. This MACS technician training program conforms to and complies with the SAE International Standard J2845 “HFO-1234yf Technician Training for Service and Containment of Refrigerants Used in Mobile A/C Systems.”
Information is provided on tanks, labels and fittings identifying R-1234yf, finding leaks, using recovery, recycling and recharging equipment, servicing procedures and what you need to know about U.S. EPA SNAP rules. What’s a SNAP rule? SNAP is an acronym for Significant New Alternatives Policy Program and discusses acceptable refrigerants for use in mobile A/C systems. Check out
While it is true that you don’t have to take the Section 609 test again to fulfill current Section 609 requirements, if you are going to work on R-1234yf mobile A/C systems you owe it to yourself and your customers to have the best and most current information and training to make smart and efficient repairs.

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Look at this beauty!

Longtime MACS member Gus Swensen serviced this 1957 Bentley yesterday, he got their A/C back in shape at Cool Car Auto Air of Columbus, GA.

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Radiator Inspection

By Chris Tyson, MACS Heavy Duty Contributor

Our fleet includes more than 180 pieces of equipment, and while we implemented a periodic inspection program many years ago, there are still times when job requirements make it impractical or inefficient to bring certain machines back to the shop as scheduled. In these situations we try to send a technician to the various job sites to check things out. We also rely on operators to perform basic functions, such as checking the oil, air in the tires, and even making minor repairs when necessary.
But, there are times when some things fall through the cracks, and that’s exactly what happened with one of our Ingersoll-Rand DD14 Rollers. This machine usually travels from job to job, and as a result, it passes through many hands along the way. By the time it showed up at the shop, we found the engine coolant was significantly low, apparently due to a leaking radiator core. Further inspection indicated the radiator had become loose in its mount, which caused it to make direct contact with the blades of the cooling fan. As you can probably guess, the spinning fan damaged the fins, eventually making a few holes in the tubes, It was at that point, about halfway down the face of the radiator, that coolant was getting out.
We’re not sure how long the roller was operated while it was low on coolant. The operators we spoke with said they didn’t notice anything wrong with the machine, and since it was cold outside at the time, we had to take them at their word.
Making these repairs was pretty much straight forward, and we decided to send the radiator out to be recored rather than replace it with a new part. Anyone who’s dealt with cooling system components for machines like these knows that sometimes they can be quite pricey, and in this case it was cost prohibitive to go with new parts. Not a big deal though, it only took our local radiator shop just a few days to complete the job. Basically what they did was power wash and clean up the old parts, desolder the tanks and replace the damaged core with a new section. After pressure testing they repainted the entire unit. The DD14 radiator now looks as good as new.

While it’s rare anymore to send an automotive radiator out for repair, it’s actually quite commonly done with trucks and off-road equipment. Part of the reason why the replacement cost is so high is because the materials used are usually copper and brass, two expensive metals, which are worth quite a bit, even on the scrap market.
We were actually lucky in this situation that no major engine damage occurred, and the lesson we learned is that properly training your team can help alert you to, or even avoid, major problems from happening. Since then we added cooling system training to our operator and crew programs, so employees can learn more about the machines they work with each day. The hope is that the more familiar they become with their equipment, how it works, and what to look for, that they can raise those red flags before it is too late.

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Coolant chemistry review

By Dave Hobbs, MACS Technical Correspondent

Ethylene glycol (EG) was green back when I was a young tech, and its formula is fairly obsolete now. Its technical name is IAT (Inorganic Additive Technology), which contained Borates, Phosphates and Silicates. Silicates (think sand) can drop out of the coolant mix and become abrasive causing leaks and worn out water pump impellers. When air (from low levels) mixed in with the coolant (cavitation) and sharp bends in the cooling system were present, the velocity of the silicates in the coolant could at times cause the abrasive damage to happen in a very short time. Reports of new heater cores beginning to leak after a few hours of run time were not urban legends. The cavitation / abrasive effect acted like a sand blaster. When you changed the old green IAT regularly, there were very few problems. Although it had decent corrosion protection in the form of additives, they did wear out.

Organic Acid Technology (OAT) became common with DEX-COOL® which became the required coolant for GM and a few other manufacturers starting in 1996 as the 5-year / 150,000-mile coolant. Often called “Long Life” or “Extended Life” coolant, OAT gives a properly maintained vehicle a long service life mainly due to the increased longevity of the coolant’s additives. The OAT formula never became the panacea of OEM coolants. Chrysler, Ford, Mercedes and some others recommend not using OAT / DEX-COOL® coolant in their late model vehicles. HOAT (Hybrid Organic Acid Technology) a.k.a. G-05® is used by those OEMs. Studying the back of a Zerex bottle gives you the notion that a simple color coding system exists; green for the old Ethylene Glycol IAT, orange for OAT and yellow for the HOAT. While this may be true for some brands of coolants, it is not an official standard. Coolant makers can use whatever color dye they like. HOAT comes in blue, pink, orange and even green on some Chrysler products. While HOAT EG does contain some silicates, the amount is less than its predecessor (conventional green IAT OAT / GM DEX-COOL® had a very rough road in the first few years). OAT / DEX-COOL® contains ethylhexanoic acid (2-EH) as a corrosive inhibitor. 2-EH is prone to damage plastics like Nylon 66 used in intake manifold gaskets and radiators. G30 OAT and Peak Global OAT do NOT use 2-EH. Air was also determined to be a major factor in causing system breakdowns. If those formulas weren’t enough, Phosphated Organic Acid Technology (POAT) came into the market in 2008-on Mazda / Ford in a dark green color.
Which coolant do you use? OEM recommended? Universal? Personally, I go with the OEM unless there is a compelling reason not to. Budget limitations for select customers and vehicles would be a primary reason. If the customer hasn’t had any problems (yet) AND they’re on a very tight budget AND are willing to change that ‘universal’ coolant on a recommended interval AND they don’t plan to try to squeak out 250K miles, many of us trying to keep customers happy will do our best to appease them without going overboard or cheap.

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