Hydrofluorocarbon-134a (HFC-134a) is the preferred replacement for Chlorofluorocarbon-12 (CFC-12) in vehicle air conditioning systems. The production of CFC-12 ended in December 1995 after CFC-12 was classified as an ozone-depleting substance. Automakers have chosen HFC-134a as a long-term replacement for vehicle air conditioning refrigerant. Vehicle manufacturers have developed retrofit kits and guidelines designed to provide the best level of performance with a new HFC-134a system. Retrofit kits are available for vehicles manufactured in the late 1980’s and early 1990’s.

The process of retrofitting a vehicle for the least cost generally calls for the following: removal of the old refrigerant; installation of new fittings; a new label; and the addition of polyalkylene glycol (PAG) or polyol ester (POE or ester) lubricant and the HFC-134a. Original equipment manufacturers (OEM) also offer OEM-warranted retrofit (where available) at a greater cost to the vehicle owner.

In selecting the retrofit that is best for the vehicle, the technician should consider the cost of the retrofit, the climate in which the vehicle operates, and the condition of the vehicle components. When considering cost, the owner should consider the age and condition of the vehicle. Vehicles that operate in extremely warm climates may not perform as well with a lower cost retrofit. In this situation, consider the installation of a larger condenser or the addition of a fan. If the vehicle components are well worn, they may not be capable of withstanding the higher pressures of HFC-134a.

A universal retrofit procedure has not been developed and there are no simple kits that provide all of the required parts, nor is there a guarantee of performance on every vehicle make and model. The Society of Automotive Engineers (SAE) provides guidance in publication number J1661.

Section 612 of the Clean Air Act, which describes the Agency's Significant New Alternatives Policy (SNAP) program requires that when retrofitting a CFC-12 vehicle for use with another refrigerant, the technician must ensure:

• Proper removal of CFC-12 prior to filling the system with HFC-134a.
• Use of dedicated EPA-approved equipment to recover CFC-12 from the system.
• Installation of unique fittings in order to minimize the risk of cross-contamination of the air conditioning system and/or the recycling equipment.
• Identification if the new refrigerant by affixing a uniquely colored label to identify the new refrigerant.
• Installation of a high-pressure compressor shutoff switch to prevent the compressor from increasing pressure until the refrigerant is vented, if the system includes a pressure relief device

The quantity of HFC-134a required to charge a system should be approximately 80-90 percent of the quantity of CFC-12 capacity in the system. In addition, the mineral oil used with CFC-12 is not sufficiently transported throughout the system by HFC-134a. Automobile manufacturers recommend PAG lubricants in vehicles retrofitted with HFC-134a. Flushing the system does not appear to be critical to the retrofit although SAE’s J1661 procedure includes flushing.

In most retrofit cases, the CFC-12 system hoses will perform satisfactorily with the HFC-134a refrigerant. The oil that is used in air conditioning systems acts as a natural barrier to permeation for the smaller HFC-134a molecules. Damaged hoses should always be replaced and unless a fitting is damaged during the retrofit, replacement is not always necessary. Lubricating O-rings during retrofit provides protection.

HFC-134a systems use either XH-7 or XH-9 desiccant and some manufacturers recommend routine replacement of the accumulator or receiver-drier. Other manufacturers recommend leaving the existing equipment in place. There is general agreement that if the vehicle has more than 70,000 miles or is five years old, replacement of the accumulator or receiver-drier is necessary.

As vehicles are retrofit, service technicians may want to consider how airflow condenser design on a particular vehicle will affect the retrofit and the higher vapor pressures associated with HFC-134a.

EPA regulations prohibit technicians from changing fittings on the same unit. EPA regulations also specify that when equipment is converted for use with a new refrigerant, the converted unit must be able to meet the applicable equipment standard set forth in the regulations. CFC-12 equipment may be permanently converted for use with HFC-134a under certain conditions. EPA intends to issue regulations placing certain restrictions on these retrofits in the future. Those restrictions may include: requiring that the manufacturer's service representative rather than the automotive service technician perform the retrofit; that a unit may only be retrofitted if retrofit procedures have been certified by an independent testing laboratory such as Underwriters Laboratories; and that an appropriate label is affixed to the unit. In addition, the retrofitted unit must meet the technical specifications of SAE standard J2210 and must have the capacity to purify used refrigerant to SAE standard J2099 for safe and direct return to the air conditioner following repairs. Currently, however, in the absence of any EPA regulations, a service facility may perform such a retrofit, or may have the equipment manufacturer's service representative perform the retrofit, as long as the fittings are changed in accordance with EPA's Significant New Alternative Policy (SNAP) program regulations. The Agency cautions technicians, however, that even though recovering a given refrigerant using permanently converted equipment is legal, it may not be technically desirable. The equipment is designed to be compatible with specific refrigerants, and incompatible materials may cause short circuits, damage to seals, and compressor failure. Technicians should check with the recovery equipment manufacturer for recommendations about the recovery of refrigerants other than the refrigerant the equipment was originally intended to recover. Conversion of recovery equipment for use with other refrigerants may also invalidate any warranties offered by the equipment manufacturer.

Technicians who repair or service HFC-134a MVACs must be trained and certified by an EPA-approved organization. If a technician is already trained and certified to handle CFC-12, he does not need to be recertified to handle HFC-134a.

Use of HFC-134a instead of CFC-12 will help facilities meet the requirements under 40 CFR 82, Subpart D and Executive Order 12843 requiring federal agencies to maximize the use of safe alternatives to class I (i.e. CFC-12) and class II ozone depleting substances, to the maximum extent practicable. In addition, the substitution of CFC-12 as a motor vehicle air conditioning refrigerant decreases the possibility that the facility will meet reporting thresholds for CFC-12 under 40 CFR 355, 370 and EO 12856. Chemicals used as substitutions should be reviewed for SARA reporting issues.

Chlorofluorocarbon refrigerants are generally inert chemicals with good materials compatibility. Refrigerants should not be mixed as they are difficult to separate and mixing can confer on the materials radically different properties compared to those of the individual gases and also may result in equipment damage.

High pressure gases should always be handled with care. Most refrigerants are inert and have low toxicity. Some hydrocarbon refrigerants are flammable. When working in a confined space, consider the use of monitoring equipment. Consult your local Industrial Health Specialist, your local health and safety personnel, and the appropriate MSDS prior to implementing any of these technologies.

• Reduces the amount of ODSs going into the environment.
• Allows for alternative refrigerant use.

• Some vehicle owners report that the air conditioning system does not perform as efficiently and effectively with HFC-134a.

The cost of conversion from CFC-12 to HFC-134a can range from $100 to $650 per vehicle depending on the vehicle type, mileage and condition of the vehicle. A low cost retrofit may be applicable if the vehicle is new and no major component changes are required. A conversion for a typical vehicle may require the replacement of dryer, hoses, seals, and lubricant, costing approximately $500 per vehicle.

The following economic analysis compares the costs associated with using CFC-12 versus HFC-134a. The analysis is based on information provided by a vehicle service shop in the southeastern U.S.:

Assumptions:

• Cost of 30lbs. drum of HFC-134a: $75.00 or $2.50/lb.
• Cost of 30lbs. drum of CFC-12: $459.00 or $15.30/lb.
• Cost of lubricating oil for CFC-12: $4.86/quart
• Cost of lubricating oil for HFC-134a: $21.86/quart
• Cost of recovery/recycling equipment is the same for both refrigerants.
• Equivalent usage rates for both refrigerants and lubricants.
• Approximately 2lbs. of refrigerant is installed per car (on average).
• Approximately 9oz. of lubricating oil (for the refrigerant) is installed per car (on average).
• Approximately 7,000 cars are serviced at a typical vehicle shop per year.
• Approximately 14,000lbs. of refrigerant is replaced each year .
• Approximately 2,000 quarts of refrigerant lubricant is used per year.

Annual Operating Cost Comparison for CFC-12 and HFC-134a

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Appropriate authority for making process changes should always be sought and obtained prior to procuring or implementing any of the technologies identified herein.

Section 609 Requirements for Motor Vehicle Air Conditioners
Section 609 Approved Equipment
Substitutes for Ozone-Depleting Substances