Handling Procedures For A/C Systems Using R-134A (10-63-93)

HANDLING PROCEDURES FOR A/C SYSTEMS USING R-134A

TECHNICAL SERVICE BULLETIN

AIR CONDITIONING SYSTEM USING R134A REFRIGERANT HANDLING PROCEDURES

Model(s): 1993 Subaru SVX

Group: Air Conditioning

Bulletin No.: 10-63-93

Date: April 12, 1993

SERVICE INFORMATION

MODELS AFFECTED

1993 Subaru 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

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 hard-ware differences from R-12 equipment.

R-134A PRESSURE/TEMPERATURE

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.

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 up arrow 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 5mm 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 ensure quality. Any PAG oil remaining in the container should be discarded in accordance with standard disposal practices.