R-134a Refrigerant A/C System
Contents
1. The NSX rubber hoses suction and discharge for the R 134a air conditioning system have inch threads therefore requiring identification labels The Legend rubber hoses have metric threads with no labels Do not substitute R 12 parts for R 134a parts you may damage the A C system Reason for Change The material for the hoses was changed to reduce the escaping of refrigerant and the entry of moisture through the hose 8of82. ACURA Service Bulletin YEAR MODEL 1993 NSX LEGEND R 134a Refrigerant A C System Starting with the 1993 NSX and Legends Acura will begin equipping cars with R 134a refrigerant A C systems The refrigerant R 12 used in car air conditioners contains CFCs Consequently R 12 refrigerant will be phased out and replaced with the new refrigerant R 134a which does not contain CFCs Air conditioners using R 134a look similar to the existing R 12 air conditioners in terms of system structure The most significant difference is the refrigerant itself This Service Bulletin explains the differences between R 12 and R 134a air conditioner systems how to identify the system components and how to service the R 134a air conditioner system NOTE Always refer to the service manual for specific model information and procedures Service Precautions Observe the following service precautions carefully when servicing R 134a air conditioner systems Only use service equipment that is U L listed and is certified to meet the requirements of SAE J2210 1991 to remove R 134a from the air conditioner CAUTION Exposure to air conditioner refrigerant and lubricant vapor or mist can irritate eyes nose and throat Avoid breathing air conditioner refrigerant and lubricant vapor or mist If accidental system discharging occurs ventilate work area before resuming service Additional health and safety information may be obtained from the refrigeran
3. couplers thread diameters and purity standards for recycled refrigerant are all different Known Suppliers and Model Numbers White Industries 01090 Kent Moore ACR4 Robinair 34700 Sun MRC450 20f8 Leak Tester Minimum Requirement The leak tester must be able to detect a leak as small as 0 5 oz per year or better Reason for New Tool R 134a refrigerant cannot be detected with an R 12 type leak tester R 134a refrigerant can only be detected with a high sensitivity tester NOTE Most leak testers for R 134a refrigerant can be used for R 12 refrigerant as well Known Suppliers and Model Numbers CPS L 780a Matco Tools AC 750 amp L 790a Hitech HISOOTEL amp HI400ATEL TIF 5050 5550 amp 5650 R 134a R 12 Air Conditioning Comparison Chart NOTE R 134a and R 12 parts are not interchangeable Be sure to use the correct parts for the specified refrigerant to avoid refrigerant leaks or A C system failure EXPANSION VALVE PIPING DISCHARGE CHARACTERISTICS Heat CONNECTION CHANGED SENSING O RING MATERIAL CHANGED mo CCT TT a EVAPORATOR HOSE p MELTING BOLT eae ENR a PRESSURE SWITCH COMPRESSOR RECEIVER DRYER CHARGE VALVE SHAPE CHANGED CONDENSER REDESIGNED INCREASED Compressor R 134a R 12 Identification R13a USE ONLY ND 8 OIL NOTE The compressor used on the R 134a air conditioning system has an identification label Do not substitute R 12 parts
4. fication Identification NSX LEGEND R134a LABEL inch threads metric threads inch threads NOTE The NSX R 134a evaporator has inch threads therefore requiring an identification label The Legend evaporator has metric threads with no label Do not substitute R 12 parts for R 134a parts Reason for Change Because R 134a has a higher pressure load than R 12 Expansion Valve R 134a R 12 Identification Identification NSX LEGEND R134a LABEL inch threads metric threads inch threads NOTE The NSX R 134a expansion valve has inch threads therefore requiring an identification label The Legend expansion valve has metric threads with no label Do not substitute R 12 parts for R 134a parts Reason for Change The set pressure for the expansion valve was changed because R 134a has a higher operating pressure 70f8 Pressure Switch R 134a R 12 Identification Identification ALUMINUM STEEL GOLD COLORED O RING H NBR O RING NBR M11 x 1 0 3 8 24 UNF Reason for Change R 134a s normal operating pressure is higher than R 12 The opening pressure for the valve was changed so the cooling of the R 134a A C system would equal an R 12 system _ Hose R 134a R 12 Identification Identification EPDM 6 12NY NYLON NSX LEGEND R134a label 4c anne aor TE i inch threads j inch threads metric threads FLANGE TYPE SEAL SHAFT TYPE SEAL FLANGE TYPE SEAL NOTE
5. for R 134a parts you may damage the A C system Compressor Seal R 134a R 12 Seal Material Seal Material H NBR NBR Hydrogenated Nitryl Butadiene Rubber Nitryl Butadiene Rubber Reason for Change The NBR type seals used on the R 12 compressors will swell and deteriorate rapidly with R 134a refrigerant causing refrigerant leaks 3of8 Compressor Refrigerant Oil R 134a R 12 Compressor Manufacturer Compressor Manufacturer Nippondenso ND Nippondenso ND Refrigerant Oil Type Refrigerant Oil Type Polyalkylene glycol PAG Mineral oil Synthetic oil Oil Name Oil Name ND 8 R 12 refrigerant oil Reason for Change The oil used for R 12 type compressors does not mix with R 134a refrigerant causing poor lubrication and compressor failure NOTE e Refer to the appropriate year and model of service manual or the compressor for the specific type of refrigerant oil e Replacement compressors are prefilled with R 134a refrigerant oil Additional refrigerant oil is not necessary Compressor Clutch R 134a R 12 Increased capacity Reason for Change The normal operating pressure for R 134a is higher than R 12 requiring a larger force to compress the refrigerant Compressor Relief Valve R 134a R 12 Identification Identification A MARK A 2 LINES 10MX15 3 8 24 UNF Reason for Change The pressure setting was changed because R 134a has a higher operating pressure than R 12 The relief valve only relea
6. ion applies contact an authorized Acura automobile dealer Refrigerant Comparison R 134a International Designation HFC 134a Hydrofluorocarbon Chemical Formula CHoFCF3 Container Fitting Size 1 2 16 ACME Container Color Light Blue Boiling Point 15 07 F 26 3 C Ozone Depletion Potential 0 0 Global Warming Potential Less than 0 3 R 134a Refrigerant Suppliers SUVA TRANS A C KLEA P SUVA TRANS A C REFRIGERANT FOR AUTOMOTIVE AIR CONDITIONERS IG LO INC 3499 Dabney Drive Lexington KY 40509 1 800 354 9061 or 1 606 264 7208 FAX 1 606 264 7914 Technical Chemical Co 10737 Spangler Road Dallas TX 75220 1 800 527 0885 FAX 214 506 7493 NOTE Only use automotive type R 134a refrigerants to ensure hardware compatibility ICI Chemicals amp Polymers R 12 International Designation CFC 12 Chlorofluorocarbon Chemical Formula CCloFe contains chlorine Container Fitting Size 1 4 Flare 7 16 20 UNF Container Color White Boiling Point 21 62 F 29 8 C Ozone Depletion Potential 1 0 Global Warming Potential 3 0 R 134a Service Tools Refrigerant Recovery Recycling Charging Center Minimum Requirement The equipment must be U L listed and certified to meet the requirements of SAE J2210 1991 for servicing R 134a air conditioner systems Reason for New Tool Refrigerants are not compatible requiring separate equipment Service
7. moisture rapidly do not remove the plugs from the receiver dryer until just before replacement keep the plugs on during dis assembly Reason for Change R 134a absorbs more moisture than R 12 The desiccant material was changed to achieve better water absorption capacity The melting bolt was also eliminated to prevent a total discharge of refrigerant into the atmosphere Piping R 134a R 12 Identification Identification NSX O RING H NBR O RING NBR S jma inch threads 0R134a LABEL inch threads LEGEND O RING H NBR u metric threads NOTE The NSX R 134a piping has inch threads therefore requiring an identification label The Legend piping has metric threads with no label Do not substitute R 12 parts for R 134a parts Reason for Change R 134a refrigerant requires the H NBR type O rings to to seal the pipe fittings 6of8 Sealing O rings R 134a R 12 O ring Material O ring Material H NBR NBR Hydrogenated Nitryl Butadiene Rubber Nitryl Butadiene Rubber NOTE The replacement O rings have an R 134a identification label on the parts package only Keep the O ring in the parts package until just before installing to avoid confusion Do not substitute R 12 parts for R 134a parts you may damage the A C system Reason for Change The NBR type O rings used on the R 12 systems will swell and deteriorate rapidly with R 134a refrigerant causing refrigerant leaks Evaporator R 134a R 12 Identi
8. ses refrigerant when the pressure is abnormally high then resets itself to prevent total discharge of refrigerant into the atmosphere 4of8 Charge Valve R 134a Dimension High pressure side as Low pressure side pg Ti M9 x 1 0 Identification Cap color light blue Service Hose Couplers HIGH SIDE HIGH SIDE I D 16 mm RED KNOB LOW SIDE LOW SIDE I D 13 mm BLUE KNOB Reason for Change To prevent charging the system with the wrong type of refrigerant R 12 Dimension High pressure side Low pressure side 3 8 24 UNF 7 8 24 UNF Identification Cap color dark red or black 0 Service Hose Couplers With High side Adapter Condenser R 134a The heat exchange performance of the condenser was increased by decreasing the tubing thickness and increasing the number of loops in the metal tubing Reason for Change Because the boiling point for R 134a is lower than R 12 the cooling capacity of the condenser was increased R 12 5 of 8 Receiver Dryer R 134a R 12 Desiccating Agent Desiccating Agent Improved Zeolite or XH 9 Silica gel or XH 5 Identification Identification NSX LEGEND 9 16 18 UNF M16X1 5 9 16 18 UNF MELTING BOLT NOTE e The NSX R 134a receiver dryer has inch threads therefore requiring an identification label The Legend receiver dryer has metric threads with no label Do not substitute R 12 parts for R 134a parts e The desiccant absorbs
9. t manufacturers Refrigerants and Oils Refrigerants R 12 and R 134a are not compatible with each other do not mix them Mixing R 12 and R 134a together even in the smallest quantities can result in air conditioner system and service equipment failure The refrigerant oils are also not compatible R 12 refrigerant oil is mineral based R 134a refrigerant uses a Polyalkylene glycol PAG synthetic based oil Mixing refrigerant oils will cause compressor failure Use only the recommended oil for the compressor Refer to the appropriate year and model of service manual for the specific type of refrigerant oil September 29 1992 VIN APPLICATION BULLETIN NO one 92 027 R 134a refrigerant and oil both have high hygroscopic properties meaning they attract and absorb moisture rapidly Observe the following instructions carefully 1 When replacing or disconnecting refrigerant lines be sure to plug or cap the lines and ports immediately to keep moisture and dust out of the system 2 Before recharging the system add the same amount of refrigerant oil removed during the recovery procedure Always use new oil from a sealed container Do not put used oil back in the container or the A C system 3 Immediately after using the refrigerant oil replace the cap on the container to avoid moisture absorption Service Equipment R 134a service equipment or vehicle air conditioner systems should not be pressure tested or leak tested
10. with compressed air Some mixtures of air and R 134a have been shown to be combustible at elevated pressures and can result in fire or explosion causing injury or property damage Never use compressed air to pressure test R 134a service equipment or vehicle air conditioner systems Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers Always use a recovery recycling charging system that is U L listed and certified to meet the requirements of SAE J2210 1991 when servicing R 134a air conditioner systems If a vacuum pump is used for evacuation in place of a recovery recycling charging system the vacuum pump must be equipped with a check valve to prevent the pump oil from backflowing into the air conditioner system Only use manifold gauges and related parts that are specially designed for R 134a pressure gauges hoses joints fittings etc Do not try to interchange parts from R 12 equipment 1992 American Honda Motor Co Inc All Rights Reserved BTB 15361 9209 1 of 8 CUSTOMER INFORMATION The information in this bulletin is intended for use only by skilled technicians who have the proper tools equipment and training to correctly and safely maintain your car These procedures should not be attempted by do it yourselfers and you should not assume this bulletin applies to your car or that your car has the condition described To determine whether this informat
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