A/C - R134A Handling Procedures
NUMBER: 10-63-93DATE: 04-12-93
APPLICABILITY: ALL 93MY SVX
SUBJECT:
AIR CONDITIONING SYSTEM USING R134A REFRIGERANT HANDLING PROCEDURES
OVERVIEW
In the coming months a major change will be incorporated in the air conditioning systems used in Subaru vehicles. This change involves the use of "Tetraflourethane" (CH2FCF3) more commonly known as R-134a as the A/C system refrigerant.
MODELS AFFECTED
1993 SVX
SYSTEM CHANGES
Major system component changes include:
^ R-134a refrigerant
^ Polyalkylene glycol (PAG) compressor lubricant
^ Compressor
^ Receiver/drier
^ Hoses and pipes
^ Thermal expansion valve
^ Seal/O-ring material
SERVICE EQUIPMENT
BECAUSE OF INCOMPATIBILITY BETWEEN R-134A REFRIGERANT/LUBRICANT AND R-12 REFRIGERANT/LUBRICANT, R-134A DEDICATED SERVICE EQUIPMENT IS NECESSARY TO PREVENT CROSS-CONTAMINATION WHEN SERVICING THE SYSTEM. The following items are required for proper R-134a service:
^ Manifold gauge set (new coupling design and hose material)
^ Recovery/recycling station
^ Electronic leak detector (calibrated for R-134a)
^ Accurate charging scale/station
^ Vacuum pump
Each of the listed items has been engineered for optimum efficiency when used on R-134a systems. SAE standards specify fitting and hardware differences from R-12 equipment.
R-134a PRESSURE/TEMPERATURE CHART
The enclosed refrigerant pressure/temperature card points out how similar R-12 and R-134a are in relation to each other. Actual system operating pressures for R-134a are virtually the same as current R-12 systems. Pressures are a function of system condenser and evaporator heat transfer capability and must be optimized for each type of refrigerant and each vehicle system.
REFRIGERANT/LUBRICANT
HFC-134a OR "R-134a" is the genetic identifier for Tetraflourethane (CH2FCF3) refrigerant used in the new A/C systems. R-134a is not compatible with R-12 mineral base lubricants. The correct lubricant for the systems used on Subaru vehicles is a "polyalkalene glycol" or PAG.
The PAG oil used in Subaru R-134a Zexel A/C systems is ZXL 100 PG(DH-PS). This oil is formulated specifically for the swash plate and wobble plate compressors used on Subaru R-134a vehicles with Zexel A/C and should never be mixed with other lubricants of any type. SOA P/N is K0010PS000, S-type PAG lubricant. As Subaru introduces other models with HFC-134a, PAG oil requirements will vary due to compressor design.
Each compressor contains the proper amount of PAG oil for the entire system application. If a compressor service replacement is needed, follow the procedure described in the "Compressor Oil" section of the applicable service manual.
R-134a refrigerant is available through normal supply sources..
SYSTEM SERVICE PRACTICES
While handling and service of R-134a/PAG lubricant is very similar to R-12/mineral oil, there are some significant differences. Refer to the ZEXEL R-134a Service Manual for a review of specific safety and handling practices.
Specific service procedures are covered in the appropriate Subaru Service Manual. Because of the changes in components and materials used in this system, there are service issues which need to be addressed:
^ When opening the A/C system, immediately cap or plug all openings to prevent contamination from dirt and air (moisture). PAG has an extreme moisture absorption rate. If the system has been left open the PAG oil remaining in the system will absorb moisture.
^ DO NOT use or depend on a sight glass for charge determination or diagnostics. R-134a and PAG lubricants do not always exhibit a "clear sight glass" even when properly charged.
^ Use only service parts expressly designated for R-134a systems.
^ Leak detection of R-134a is difficult even with the most sensitive electronic detectors. Move slowly and keep the sensor tip of the detector within 5 mm of the area being checked.
^ NEVER mix different grades of PAG oils or mix PAG oil with mineral oil in any A/C system. Compressor failure will occur.
^ System evacuation time should be doubled for R-134a in-service systems as compared to new systems.
^ PAG oil is supplied in single use (small quantity) containers to insure quality. Any PAG oil remaining in the container should be discarded in accordance with standard disposal practices.
ADDITIONAL INFORMATION
Service parts information and service procedures are covered in the respective Genuine Subaru Parts and Service publications. A ZEXEL R-134a Service Manual is included with this mailing which covers R-134a technical issues and practices in detail. Assistance is available from your DTM regarding A/C system training and specific service issues concerning R-134a A/C systems.