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Home >   How To >   How to Repair AC Parts >   Sanden AC Compressor: R134a Important Information

Sanden AC Compressor: R134a Important Information

R134a/PAG Oil Handling Precautions:


As a conscientious member of the global community, Sanden Corporation with its subsidiaries is committed to the elimination of CFC-based refrigerant. This manual focuses on the service information for Sanden compressors intended for use with R134a and PAG oils.


1. Always follow the safety precautions as suggested by the manufacturer.


2. Do not discharge R134a into the atmosphere. Even though its ozone depletion potential is zero, it does have a global warming potential. Recovery and recycling are mandated by the Clean Air Act. Use recovery equipment designated only for R134a. Never introduce another refrigerant into the R134a equipment.


3. Never mix R134a with other refrigerants or A/C system failure is likely to occur.


4. Use only Sanden specified PAG lubricants for R134a systems using Sanden compressors. If other lubricants are used, A/C system failure is likely to occur.


5. Never introduce R134a or PAG oil into a system not designed for them except when following the appropriate retrofit procedure described in the section “Converting R-12 Systems to R134a” below.


6. The Sanden specified PAG oils used in R134a systems absorb atmospheric moisture very quickly. Moisture in the A/C system can cause major damage or failure.


a) Never leave PAG oil exposed to air for a prolonged time. Tightly reseal the oil container immediately after each use.

b) During A/C system repair, cap all fittings as soon as opened and leave capped until just before they are reconnected.

c) If a repair is performed on an R134a compressor or system, evacuate the system for at least 45 minutes before recharging to ensure the removal of moisture which may have been absorbed by the PAG oil in the compressor and system.


Table of Saturation Temperatures and Pressures:


-40 -7.2 in. Hg 25 22 105 135
-30 -4.8 in. Hg 30 26 110 147
-20 -1.7 in. Hg 40 35 115 159
-15 0 50 45 120 172
-10 2 60 57 130 200
-5 4 70 71 140 231
0 6 80 85 150 264
5 9 85 95 160 301
10 12 90 104 180 386
15 15 95 114 200 485
20 18 100 124 210 549




Recommended Procedures For Sanden R-12 Compressors Retrofitted With R134a


The use of R134a in mobile A/C systems designed for R-12 refrigerant use causes higher discharge pressures (as much as 10-15%) and necessitates changing the compressor lubricant from mineral oil (5GS) to PAG oil (Sanden's SP-10 or SP-20) to ensure compatibility.


These changes result in greater wear to the internal compressor. Therefore. to ensure consistent and expected reliability. Sanden does not recommend using R134a in systems and compressors designed for R-12.


However, Sanden recognizes the realities of the automotive service markets and consumer preferences. If a retrofit is required, please follow the vehicle manufacturers' published retrofit procedures. Ensure all work done complies with SAE recommended practices as described in J1660 & J1661:


a) Repair any problems or leaks before retrofitting.

b) Affix labels to the vehicle showing conversion status.

c) Observe all safety recommendations.


If an OEM retrofit procedure is not available, Sanden recommends the following procedure:


Sanden's Procedure for Conversion from R-12 to R134a:


1. If the R-12 vehicle air conditioning system is operational, run it at idle with the A/C blower on high speed for five (5) minutes to maximize the amount of oil in the compressor.


2. Recover all R-12 refrigerant from the vehicle's A/C system.


3. Remove the compressor from the vehicle.


4. Remove the compressor oil plug and then drain as much mineral oil as possible from the compressor body.


5. Drain mineral oil from the cylinder head suction and discharge ports while turning the shaft with a socket wrench on the clutch armature retaining nut.


6. Remove the existing R-12 receiver-drier or accumulator-drier from the vehicle and discard. Allow as much oil as possible to drain from the A/C hoses.


7. Change any O-rings on the receiver-drier or accumulator-drier joints to approved HNBR O-rings: replace any other O-rings that have been disturbed.


8. Replace the receiver-drier or accumulator-drier with a new R134a compatible one containing XH7 or XH9 desiccant.


9. If a CCOT system is being repaired due to compressor damage, or foreign material is found in the oil drained from the system, this foreign material must be removed from the system. At this time an in-line filter should be installed in the liquid line. Allow as much oil as possible to drain from the A/C lines when installing the filter. Change any O-rings disturbed in the installation of the filter to approved HNBR O-rings.


10. Perform any necessary repairs to the compressor or A/C system.


11. Using the original refrigerant of quantity specification, add SP-20 or SP-10 oil to the compressor (SP-10 for TR, SOV-710, SDB-705, SDB-706, and SDB-709; SP-20 for all other SD compressors).


12. Replace the compressor oil plug O-ring with an HNBR O-ring.


13. Reinstall the compressor oil plug. The plug seat and O-ring must be clean and free of damage. Torque the plug to 11-15 ft•lb (15-20 N•rn, 150-200 kgf•cm).


14. Change any seals at the compressor ports to approved HNBR seals.


15. Reinstall the compressor to the A/C system. Evacuate the A/C system for at least forty-five (45) minutes to a vacuum of 29 in. Hg, using R-12 equipment, to remove as much R-12 as possible from the residual mineral oil.


16. Remove all R-12 service equipment and disable the R-12 service fittings to prevent any refrigerant other than R134a from being used. Permanently install R134a quick connect service fittings to the A/C system.


17. Connect R134a service hoses and other equipment. Re-evacuate the system for thirty (30) minutes using the R134a equipment.


Ambient Temperature Pressure Reading Chart:


R-134 Temperature Pressure Chart
Temperature ℉/℃
Low Pressure Gauge High Pressure Gauge
65℉ (18℃) 25-35 psi / 172-241 kPa 135-155 psi / 931-1069 kPa
70℉ (21℃) 35-40 psi / 241-276 kPa 145-160 psi / 1000-1103 kPa
75℉ (24℃) 35-45 psi / 241-310kPa 150-170 psi / 1034-1172 kPa
80℉ (27℃) 40-50 psi / 276-345kPa 175-210 psi / 1207-1448 kPa
85℉ (29℃) 45-55 psi / 310-379kPa 225-250 psi / 1551-1724 kPa
90℉ (32℃) 45-55 psi / 310-379kPa 250-270 psi / 1724-1862 kPa
95℉ (35℃) 50-55 psi / 345-379kPa 275-300 psi / 1896-2068 kPa
100℉ (38℃) 50-55 psi / 345-379kPa 315-325 psi / 2172-2241 kPa
105℉ (41℃) 50-55 psi / 345-379kPa 330-335 psi / 2275-2310 kPa
110℉ (43℃) 50-55 psi / 345-379kPa 340-345 psi / 2344-2379 kPa
Ambient Temp is the Outside Atmospheric Temperature


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