Many of the most versatile collision shops incorporate air conditioning (A/C) and heating service as a stand-alone profit center. Who has a better opportunity to retrofit a vehicle in need of a condenser or a compressor –– thanks to physical damage discovered at the pre-estimate inspection –– than those who’ll replace these major components during a collision repair procedure? Transferring a system from the outdated and environmentally harmful R-12 to the EPA-accepted R-134 is a profit center built into the description of the collision shop itself.

But finding ways to better understand today’s climate-control systems can be challenging for even the most accomplished service technicians. To get you started, we’ll look at some of the hills and valleys that currently exist within the confines of A/C service when maintaining an A/C profit center.

Reviewing Basics
The first auto air conditioner was installed in a Packard in 1940. Since then, a lot of change has come about, but the physical principles remain the same. Any time we cool, heat, re-heat, dehumidify, clean, filter, circulate, re-circulate and/or change the quality of air moving within the vehicle’s interior space, we should understand that we’re dealing with sophisticated components commonly referred to as a heating, ventilation and air conditioning (HVAC) system.

Physical principles that govern the refrigeration cycle haven’t changed much since the 1940s. Convection refers to heat flow from a hot surface to a cooler one. Heat rises as it’s expelled or shed by an object in free space. As the heated air rises, cooler air will flow into its previously occupied spot, taking its place.

Evaporation refers to molecules on the surface of a liquid escaping to the open air as they transform to a gas. For example, heating water to 212 degrees F causes the water molecules to evaporate slowly. Water vapor is formed, and as the temperature increases, the molecules transform into a gaseous state at a higher rate. When enough heat energy is utilized and added to a liquid, the liquid becomes unstable and the molecules literally fly out of the liquid in its confined state.

The large expenditure of energy required to get a liquid to “boil off” like this is referred to as the “latent heat of vaporization,” where a change of state occurs without a change in temperature. Therefore, the liquid cannot absorb any further heat process without giving up all its molecules to change to a gaseous state. It’s the principles of physics that refer to this latent heat just discussed that provide the foundation for the A/C cycle utilized to cool the vehicle interior.

The Refrigeration Cycle
Heat is convected toward the evaporator core inside an automobile, aided by the blower pulling the air across the fins of the core itself. As the liquid refrigerant evaporates, heat is absorbed into it and moved to the compressor inlet. The heat is then pumped in vapor form and pressure is increased toward the condenser located at the front of the vehicle, usually directly behind the grill. While passing through the condenser, the heat is then given up and exchanged for the cooler air passing through the condenser and radiator. This process causes the vapor to cool rapidly and return to its liquid state. In a nutshell, this cycle is repeated constantly as long as the refrigerant is pumped throughout the system.

Converting for Profit
Let’s examine a typical conversion of a system designed to use R-12 to one using the only EPA-approved refrigerant substitute, HFC-134. Early vehicles, such as those produced in the mid to late 1970s, should have compressors either re-sealed or replaced. The tendency of the 134 molecule to leak out of a system that may have contained R-12 is notoriously common. Old hoses may not have to be changed, but all of the mineral oil used as a lubricant for the compressor must go. The majority of this material will be flushed out using a process called closed loop flushing, which requires the insertion of a flushing machine into the refrigerant loop of the vehicle.

On newer cars, the hoses that came with the R-12 system can be re-used because the R-12 oil has penetrated the inner jacket and set up a leak-proof glaze over time as heating and cooling took place under the hood. Lubricants for R-134 are factory-installed poly akeylene glycol (PAG) or esters in organic or synthetic form as a complete replacement substitute. Systems using R-12 and mineral oil can use esters, but flushing is still recommended any time a new oil is installed to keep sludge from breaking loose and blocking up the system.

The very strict rules of the conversion process not only specify that 134 is the single acceptable substitute for R-12 at this time, but also that new fittings be installed into the system. Companies that produce the conversion kits provide the fittings, sealing caps, and directions for installation and disabling the old R-12 items.

Another thing to consider is that the R-134 system will run higher pressures for any given circumstance all the time. The R-134’s ability to remove heat from a system at the same rate of efficiency as an R-12 system depends upon moving the R-134 through the system in the same manner, but with a reduced overall volume and with higher temperatures and pressures.

Shops doing late-model conversions see very few problems, since compressors and hoses can normally remain untouched for the conversion. The older model cars sometimes shell an R-12 compressor if the unit isn’t able to pump at a high pressure that comes with the installation of R-134. If a hose must be replaced, use a barrier hose, standard on most vehicles equipped with R-134.

Follow factory recommended procedures with regard to desiccants. In this case, use an XH-5 (or updated dual-use version) for R-12-only restoration. The XH-7 or XH-9 is the way to go when converting or restoring to R-134.

It’s good practice to replace the filter dryer during a conversion. Be sure the factory sealing plugs are kept in place while the parts wait to be installed. Body shops must remember to store replacement kits in a clean, dry area that isn’t exposed to organic or other solvent contamination.

The magic number is 70,000 miles when servicing a system brought in for an R-134-only re-charge, perhaps as a result of a collision-related repair. Sell the customer on this service as a preventative measure. If the customer chooses to ignore the manufacturer’s directives by time/mileage, be sure to have him waive your responsibility, keeping you off the hook if the system doesn’t cool like it was designed to.

An Ounce of Prevention
Body and paint shops that strive to make the A/C segment a real profit center need to look at each collision-related job as an opportunity to either restore a leaking system or upgrade a system in need of a major component because of the collision to the R-134 option.

In 1994, the EPA incorporated the Significant New Alternative Policy (SNAP), which governs the many refrigerant-wannabe substitutes that might exist in the marketplace. So far, the EPA doesn’t recognize any of the substitute refrigerants as a “drop-in replacement” for R-12. But it has assigned the status of “acceptable substitutes” to several of these based upon criteria it calls “subject use conditions.” While not sanctioning the particular refrigerant as a good or better upgrade than R-134, the EPA does see the particular refrigerant as a substitute when used as follows:

• The refrigerant is used instead of R-12 to restore a system to function while not endangering human health or safety.

• The replacement refrigerant must be assigned a code by the EPA and be tracked as such. This also requires special and unique servicing fittings, with special labels different from those in use in R-12, R-134 or any other specific refrigerant already recognized as an alternative by the EPA. This quickly gets crazy since you need an entirely different set of service equipment to handle the alternative. (You can’t mix any of the refrigerants for any reason inside the vehicle operating system.) Specific hose ends, labels and other items related to equipment are also required.

The pressure temperature relationship between the new and old refrigerant may dictate a new pressure switch or cycling clutch setting different from any associated with R-134 or R-12. Another big consideration is that the EPA doesn’t endorse or approve any of the substitutes. It only reviews the data it receives from various manufacturers. This means that most of the liability incurred by using such a refrigerant substitute is firmly on your shoulders, even if you provide the adequate “subject usage” activity required by the EPA.

Learn from Experience
Collision shops should be cautious before switching to a high volume system when converting from R-12 to HFC 134. Such a situation would be a vehicle with two or more evaporators operating at marginal efficiency level with R-12. This conversion can be a losing proposition because R-134 won’t work as well as R-12 does at absorbing heat by nature. The expense to upgrade the vehicle equipment as well as the cooling system makes the switch very costly. Any other system that uses at least 6 pounds of R-12 will also suffer from the same problems as above. If you have no other choice but to upgrade — and the vehicle is out of warranty — the customer should be made aware of the existence of substitutes, but don’t recommend any by name or brand.

General Motors (GM) cars and light trucks should have cycling clutch switches adjusted to 21 to 23 psi at the cycle off condition. Since the R-134 volume is lower but the pressure is higher, the system will work in sync if this adjustment is performed after conversion. A high-pressure switch that controls radiator fan temperatures in some GM and other cars must be changed to a lower setting, and a higher setting cut-switch should be used to prevent refrigerant venting from the system relief valve. Some higher-end GM cars can suffer from phantom codes if the evaporator sensor indicates a low flow condition it thinks is related to a clogged tube. Replace — don’t jumper — the sensor with a new, upgraded item in such cases. Clear out other GM codes before trying to restore the system, since the compressor clutch may not come online if a code is present.

Fords and Chryslers — with no provision for auxiliary or heavy-duty cooling — have an extra cooling fan to lower the condenser temperature and corresponding pressure. Always choose a larger condenser at a collision replacement interval if the vehicle is obviously used for towing, upgrading toward HFC-134 on Ford rear drive trucks and/or vans.

Adjust evaporator temperature switches to control clutch cycling on all front-wheel drive vehicles and those of the rear-wheel drive variety when the problem of rapid on/off cycling occurs after a retrofit.

On The Shelf
The cost of refrigerant as well the rules governing how much refrigerant you can have on-hand make maintenance of any large amount of R-12 or R-134 a bad idea. Something called a floor tax — assigned by the government — is designed to keep any existing R-12 in circulation –– and not sitting around the shop. This makes the expense of hoarding the stuff higher than marketable levels, so it doesn’t pay to keep much on hand. Shop owners should have the popular retro-fit kits for domestic vehicles on the shelf.

Other items that can be added to the profit center include a green style O-ring assortment, so the seals will work with either R-12 or R-134 systems; special gaskets and seals for popular compressor replacement; an assortment of extra fittings and schrader valves; and maybe even a quart or two of the various viscosities of mineral oils. Also, keep some ester on hand, a couple grades of PAG oil, a universal filter-dryer and desiccant units. Orifice tubes always get clogged and should be changed at retrofit time.

UL- and ETL-Approved Equipment
Service equipment required for the profit center is a substantial investment, but it’s a requirement by law if you repair systems and remove refrigerant for service or repair reasons. New rules allow transport of in-shop equipment, so you might get along without some of the gear for awhile.

It’s often difficult to find an affordable company that wants to do your refrigerant recovery and handling without the benefit of keeping the refrigerant for themselves. The possibility of contamination by an unknown refrigerant will always be an issue, and you’ll be better off in the long run owning your own equipment.

You’ll need to decide on stand-alone systems — in other words, a separate service machine for recovery, recycle, purge, evacuate, leak test and re-charge of R-12 and R-134. Or it can be a Siamese or dual-function system that links two separate machines together. You may choose to have a single system that shares a few components, such as the vacuum pump and weight scales. The latter type of machine is more compact but is generally harder to keep from getting contaminated.

Filters and other critical areas are still completely separate, and in either of the system types, manual, partial automatic or full microprocessor control over any or all of the service functions is available for extra cost.

Meeting Certain Conditions
With all the requirements and regulations on A/C units, is it worth the effort as a profit center? That depends on you. Chances are, having to cut through all the red tape keeps many shops away from such a profit center. But with fewer shop owners taking on the challenge, that means you can get a bigger slice of the pie.

Just about every car on the road comes with A/C, which means that’s one more item that will eventually need fixed. If you think you can handle the challenge, then your A/C profit center may offer you lots of cool cash.

Writer Bob Leone, a retired shop owner and contributing editor to BodyShop Business, is ASE Three-Way Master Certified and is completing qualifications as a post-secondary automotive instructor in the vocational-school system in Missouri.

UL Specifications Here’s a typical set of specs for a versatile operating unit approved by UL: • Operating Temperature –– 50 to 120 degrees F • Relative Humidity –– up to 80 degrees F non-condensing • Operating Pressure Range –– 30 in Mercury to 300 psi • Manifold Gauge Set Range –– high side to 500 psi, low side to 300 psi • Refrigerant charge amount –– 0 to 25 pounds • Recovery Amount –– 0 to 25 pounds • Compressor — 1/3 to 1/2 hp • Condenser –– fan cooled • Recovery Rate –– typically 1 pound per minute maximum • Control panel gauge –– maximum 400 psi • Control panel temperature gauge –– 0 to 60 degrees F

Training Resources • Mobile Air Conditioning Society (MACS): (215) 679-2220 • International Mobile Air Conditioning society (IMAC): (817) 338-1100. • Inter-Industry Conference on Collision Repair (I-CAR): United States (847) 590-1191, Canada (416) 299-4227 • The Stratospheric Ozone Information Hotline, an industry-related information exchange: (800) 296-1996, or via the Internet at (www.epa.gov/ozone). In addition to these primary industry trainers, many parts manufacturers, as well as specialty trainer and tool group companies, provide individualized training on automotive A/C systems. Check with your area vo-tech institution for other certified programs, as well as your local jobber or parts supplier for further information.

Rules for Recovery and Recycling Under Section 609 of the established Clean Air Act, the rules for refrigerant handling and substitute refrigerants were given a priority issue status. The following items should be reviewed by any and all who handle refrigerant in an autobody and paint shop: • R-12 and R-134 must be recycled. • Equipment must meet appropriate SAE standards for either dual equipment shared refrigerant machines or separate standards for R-12 or R-134 stand-alone machines. • All equipment must meet industry approval standards and comply with UL or ETL regulatory standards. • New HFC-134 certifications are specified for those not already certified in an EPA-approved category for an approved program. Those already certified under a previous R-12 only program aren’t required to certify as in the R-134 program. The certification programs themselves will undergo some basic changes under Section 609 and include the following mandatory compliances: • The program must include information and testing on retrofitting of R-12 to another refrigerant. This will include data on retrofits involving SNAP programs specific guidelines. • Handling of the refrigerants now available in the marketplace will be emphasized, and requirements for working with and disposing of contaminated refrigerants will be spelled out. • Refrigerant “blends” will be adequately covered. Their impact on system operation and vehicle and occupant safety will be examined. • The use of a leak detector and other refrigerant identifiers will be designated to provide a margin of control for sensitivity limits, etc. (see J-1627 SAE standard). Recycling — as defined in Section 609 — is when refrigerant is re-handled with portable equipment at the user level. Recycled refrigerant isn’t considered as pure as reclaimed refrigerant that’s handled and recycled off-site by more sophisticated equipment. Reclaimed refrigerant must actually restore the essence of the refrigerant to like new. New rules give you the option of obtaining “salvage yard”-designated refrigerant for recycling at the user level. The crux of the law, however, states that severe restrictions on this practice will be in effect to minimize cross-contamination of refrigerants and their service equipment.

Enforcement of Regulations • EPA Enforcement –– This has been recognizably consistent. Of the 300 facilities inspected in 1998 and the 300 inspected in 1999, only 43 received “orders to comply.” Eleven of those facilities were assessed fines. • Restrictions on Buying Refrigerants –– R-12 can only be purchased by a licensed facility employing Section 609-certified techs. At this point, HFC-134 can still be openly purchased by anyone. This, however, is destined to change soon, and restrictions could come as early as this summer. • Odds and Ends –– The chance a vehicle is equipped with a refrigerant blend that might contain significant amounts of a flammable and otherwise dangerous-to-inhale gas has not escaped the EPA. Tests are currently being considered to determine exposure levels in the passenger compartment of any given vehicle. According to some sources, this could sound the “death knell” for many of the alternatives currently marketed.