If it is the old style york compressor ( up top on left) dont bother it wont cool. Now if you have an r4 ( bottom right) you will be ok. Make sure to add pag oil only to the compressor and change reciever drier. Use a 15-20% less charge of 134a than it takes r12. When doing a conversion we usually change e-valve and condensor if the car has experienced a black death ( compressor lock up) . Good luck

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euro 287
Mercedes Technician 7 Years (retired to Hyundai)
2000 Dodge Durango
98 Mazda truck