How Aircond Works1

8/13/2019 How Aircond Works1

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Air Conditioning, Page 2 of 3

inks to topics on page 1

Theory of air conditioning

How the air conditioner works


Governmental regulations


Air conditioning safety precautions

System service and repair

Air conditioning maintenance

System inspection

Special section: Air conditioning system maintenance intervals

Special section: Troubleshooting air conditioning problems

Governmental regulations

Our threatened ozone layer ee Figure 3

he ozone layer acts as a blanket in the stratosphere that protects us from harmful ultraviolet (UV) radiation.cientists worldwide believe that man-made chemicals such as CFC-12 (also known by the trade name Freon)re rapidly destroying this layer of gas 10-30 miles (16-48 km) above the earth's surface. Strong UV radiationreaks the CFC-12 molecules apart, releasing chlorine. A single chlorine atom can destroy over one hundredhousand ozone molecules. Ozone loss in the atmosphere is likely to lead to an increase in cataracts and skinancer, which is now one of the fastest growing forms of cancer, and could weaken the human immune system.n the U.S., one person dies of skin cancer every hour. Agriculture, as well as plant and animal life, may also beramatically affected.

Remember that ozone is "good up high, bad nearby." Even though it protects us when it is in the stratosphere,zone at ground level can be harmful to breathe and is a prime ingredient in smog. Many man-made sourcesuch as tailpipe emissions from vehicles contribute to ground-level ozone.

Reference Library Feature Articles Car Care Encyclopedia Automotive Glossary Collision & Auto

Figure 3 Refrigerant released into the atmosphere causes harm by depleting theozone layer, which protects us from ultra violet rays of the sun.

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Global action to protect the ozone layer

he United States has joined over 160 countries as a party to the international treaty known as the Montrealrotocol. All developed countries agreed to phase out production of most ozone-depleting substances, includingFC's, by the end of 1995. The 1990 Clean Air Act Amendments (the Act) incorporated this production ban datend directed the EPA to develop regulations to maximize recycling, ban nonessential uses, develop labelingequirements and examine safe alternatives for ozone-depleting substances.

mpact of motor vehicle air conditioners

One of the largest uses of CFC-12 in the U.S. is as a refrigerant in Motor Vehicle Air Conditioners (MVACs).ection 609 of the Act gives the EPA the authority to establish requirements to prevent the release ofefrigerants during the servicing of MVACs and to require recycling of refrigerants. Widespread refrigerantecycling reduces the demand for virgin CFC-12 and thus extends the time that it will be available. The following

ections describe the requirements of the law and its potential impact on the service industry.

Handling CFC-12

Venting

Another section of the Clean Air Act, section 609, prohibits releasing CFC-12 into the atmosphere. Therohibition on venting CFC-12 has been in effect since 1992.

ection 609 regulatory history

he original regulation promulgated under section 609 was published in July 1992. That regulation establishedtandards for equipment that recovers and recycles CFC-12 refrigerant from motor vehicle air conditioners,ules for training and testing technicians to handle this equipment, and record-keeping requirements for serviceacilities and for refrigerant retailers. A supplemental final rule published in May 1995 established a standard forquipment that recovers but does not recycle CFC-12, as well as training and testing technicians to handle thisquipment.

Approved equipment

echnicians repairing or servicing CFC-12 MVACs must use either recover/recycle or recover-only equipmentpproved by the EPA. Recover/recycle equipment cleans the refrigerant so that oil, air and moistureontaminants reach acceptably low levels. A list of approved recover/recycle and recover-only equipment is

vailable from the EPA.

echnician training and certification

echnicians who repair or service CFC-12 motor vehicle air conditioners must be trained and certified by anPA-approved organization. Training programs must include information on the proper use of equipment, the

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egulatory requirements, the importance of refrigerant recovery, and the effects of ozone depletion. To beertified, technicians must pass a test demonstrating their knowledge in these areas. A list of approved testingrograms is available from the EPA.

Record-keeping requirements

ervice centers must certify to the EPA that they own approved CFC-12 equipment. If refrigerant is recoverednd sent to a reclamation facility, the name and address of that facility must be kept on file.

ales restrictions

ee Figure 4

ection 609 has long prohibited the sale of small cans of ozone-depleting refrigerants to anyone other than aertified technician. The sale of any size container of CFC-12 to anyone other than certified technicians wasrohibited under section 608 of the Act beginning on November 14, 1994. This provision is intended toiscourage "do-it-yourselfers" who recharge their own air conditioners. Such individuals often release refrigerantecause they typically do not have access to recovery/recycling equipment. The EPA encourages "do-it-ourselfers" to bring their vehicles to certified technicians who can properly fix air conditioners using approvedquipment. This avoids damage to A/C equipment by improper charging and helps to protect the environment.

Handling HFC-134a refrigerant

Venting

ection 609 of the Clean Air Act prohibits releasing HFC-134a into the atmosphere. The prohibition on ventingHFC-134a has been in effect since November 1995.


n March 1996, the EPA proposed a rule to require recycling of HFC-134a. The rule proposed standards forecover-only and recover/recycle equipment and rules for training and testing technicians to handle thisquipment.

Approved equipment

Because of the venting prohibition described above, technicians who repair or service HFC-134a MVACs must

ecover the refrigerant. Any equipment may be used to recover the refrigerant, since equipment standards willot be in place until the effective date of the final rule. Technicians are not required to recycle HFC-134aefrigerant until the effective date of the final rule. At that time, technicians handling HFC-134a will have toither recycle the used HFC-134a refrigerant on-site, or send it to an off-site reclamation facility to be purifiedo ARI Standard 700, before it can be used to recharge A/C equipment.

Figure 4 Common recovery machine used on R-134a systems.

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After the effective date of the rule, the EPA will make available a list of approved recover/recycle and recover-nly HFC-134a equipment.

onverting CFC-12 equipment for use with HFC-134a

PA regulations prohibit technicians from changing fittings on the same unit back and forth so that the unit issed for CFC-12 in the morning, HFC-134a in the afternoon, then back to CFC-12 again, etc.

PA regulations specify that when equipment is converted for use with a new refrigerant, the converted unitmust be able to meet the applicable equipment standard set forth in the regulations. CFC-12 equipment may be

ermanently converted for use with HFC-134a under certain conditions. The EPA intends to issue regulationslacing certain restrictions on these retrofits in the future. Those restrictions may require that themanufacturer's service representative rather than the automotive service technician perform the retrofit, that anit may only be retrofitted if retrofit procedures have been certified by an independent testing laboratory suchs 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 usedefrigerant to SAE standard J2099 for safe and direct return to the air conditioner following repairs.

n the absence of any EPA regulations, a service facility may perform such a retrofit, or may have thequipment manufacturer's service representative perform the retrofit, as long as the fittings are changed inccordance with the EPA's Significant New Alternative Policy (SNAP) program regulations. The Agency cautionsechnicians, however, that although recovering a given refrigerant using permanently converted equipment is

egal, it may not be technically desirable. The equipment is designed to be compatible with specific refrigerants,nd incompatible materials may cause short circuits, damage to seals, and compressor failure. Technicianshould check with the recovery equipment manufacturer for recommendations about the recovery ofefri gerants other than the refrigerant the equipment was originally intended to recover. Conversion of recoveryquipment for use with other refrigerants may also invalidate any warranties offered by the equipment

manufacturer.


Before the final rule is published and goes into effect, technicians repairing or servicing HFC-134a MVACs do noteed to be trained and certified to handle HFC-134a. After the effective date of the rule, however, technicians

who repair or service HFC-134a MVACs must be trained and certified by an EPA-approved organization. If a

echnician is already trained and certified to handle CFC-12, he will not need to be recertified to handle HFC-34a.


ervice centers must certify to the EPA that they own approved HFC-134a equipment.

his certification is a one-time requirement, so that if a service center purchased a piece of CFC-12ecycling equipment in the past, and sent the certification to the EPA, the service center does noteed to send a second certification to the EPA when it purchases a second piece of equipment, no

matter what refrigerant that equipment is designed to handle. If refrigerant is recovered and sent toreclamation facility, the service center must retain the name and address of that reclaimer.

ales restrictions

At the time of publishing, there is no restriction on the sale of HFC-134a, so anyone may purchase it. The EPAwill issue a proposed rule under section 608 of the Act that will include a proposal to restrict the sale of HFC-34a so that only technicians certified under sections 608 and 609 may purchase it. After the proposed rule isublished, the EPA will review comments from the public on the proposal and will then publish a final ruleometime in late 1998.

Handling other refrigerants that substitute for CFC-12

Venting substitute refrigerants

Other than HFC-134a, all EPA-accepted refrigerants that substitute for CFC-12 in motor vehicles, and that areurrently on the market, are blends that contain ozone-depleting HCFC's such as R-22, R-142b and R-124.ection 608 of the Clean Air Act prohibits venting any of these new blend substitutes into the atmosphere. Therohibition on venting these ozone-depleting blends has been in effect since 1992.

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When the March 1996 proposed rule that requires recycling of HFC-134a was published in final form in theummer of 1997, it also established a standard for equipment that is designed to recover, but not recycle, anyingle, specific blend substitute refrigerant.

Recover-only equipment

echnicians recovering these blend refrigerants must use EPA-approved equipment. As noted above, the finalule contains a standard for equipment designed to recover, but not recycle, a single, specific blend refrigerant.

may be possible to convert a piece of CFC-12 recover-only equipment so that it meets this standard-see theiscussion on equipment conversions that follows this topic.

he EPA is currently working with independent testing laboratories and with equipment manufacturers to devisequipment that can recover, but not recycle, not only multiple blend refrigerants, but also contaminated CFC-12nd HFC-134a. Within the next year, the EPA will propose a standard for this type of equipment. The EPAxpects that this equipment should be available by the 1998 A/C season.

onverting CFC-12 recover-only equipment for use with blend substitutes

he EPA regulations prohibit technicians from changing fittings on the same unit back and forth so that the units used for CFC-12 in the morning, a blend substitute in the afternoon, another blend substitute the next

morning, HFC-134a the next afternoon, etc.

he EPA regulations specify that when equipment is converted for use with a refrigerant other than theefrigerant for which the equipment was originally intended, the converted unit must be able to meet thepplicable equipment standard set forth in the regulations. CFC-12 recover-only equipment may be permanentlyonverted for use with single, specific blend refrigerants under certain conditions. The EPA intends to issueegulations placing certain restrictions on these retrofits in the future. Those restrictions may require that the

manufacturer's service representative rather than the automotive service technician perform the retrofit, that anit may only be retrofitted if retrofit procedures have been certified by an independent testing laboratory suchs Underwriters Laboratories, and that an appropriate label is affixed to the unit. In addition, the retrofitted unitas to meet the technical specifications of the EPA standard.

Recycling equipment

he EPA regulations currently prohibit technicians from recycling blend substitute refrigerants, and the Agencys not aware of any equipment currently on the market designed to recycle any of these blends. After recoveringhe blend refrigerant from the MVAC system, it must, therefore, be sent off-site for reclamation.

he EPA is working with independent testing laboratories and with equipment manufacturers to determinewhether recycling equipment can be developed to service these blends, without jeopardizing the health orafety of the technician and the integrity of the MVAC system. If it is possible to develop such equipment, thePA will work with equipment and refrigerant manufacturers and with independent testing laboratories toevelop an appropriate standard for the equipment.

onverting CFC-12 recover/recycle equipment for use with blend substitutes

At the time of publication, the EPA also currently prohibits the conversion of existing CFC-12 or HFC-134aecycling equipment for either temporary or permanent use with a blend refrigerant. In the future, the EPA mayssue regulations allowing these conversions but placing certain restrictions on who performs the conversions,

what models may be converted, etc.


echnicians who repair or service MVACs with these refrigerants must be trained and certified by an EPA-pproved organization. If a technician is already trained and certified to handle CFC-12 or HFC-134a, he will not

eed to be re-certified to handle the blend refrigerants.


ervice facilities that work on vehicles that use blend substitutes must certify to the EPA that they ownpproved equipment designed to service these refrigerants. Note that this certification is a one-time

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equirement, so that if a service center purchased a piece of CFC-12 or HFC-134a recycling equipment in theast, and sent the certification to the EPA, the service center does not need to send a second certification to thePA when it purchases a second piece of equipment, no matter what refrigerant that equipment is designed toandle. If refrigerant is recovered and sent to a reclamation facility, the service center must retain the namend address of that reclaimer.

ales restrictions

Because these blends contain HCFC's, Section 608 regulations prohibit the sale of any size container of any ofhese blend refrigerants to anyone other than certified technicians. This prohibition began in November, 1994.

Retrofitting vehicles to alternative refrigerants

Although section 609 of the Act does not govern retrofitting, section 612 of the Act, which describes the EPS'significant New Alternatives Policy (SNAP) program, does require that when retrofitting a CFC-12 vehicle for use

with another refrigerant, the technician must first extract the CFC-12, must cover the CFC-12 label with a labelhat indicates the new refrigerant in the system and other information, and must affix new fittings unique tohat refrigerant.

n addition, if a technician is retrofitting a vehicle to a refrigerant that contains R-22, the technician mustnsure that only barrier hoses are used in the A/C system. Finally, if the system includes a pressure reliefevice, the technician must install a high-pressure compressor shutoff switch to prevent the compressor from

ncreasing pressure until the refrigerant is vented.

Revisions to the Section 609 rules and regulations

Although these rules were current at the time of publication, revisions and additional information can bebtained through the Environmental Protection Agency. Contact the EPA through their hotline (800) 296-1996,r on the World Wide Web at http://www.epa.gov/ozone

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