Cadillac Repair: 1992 cadillac AC, 134a freon, r12 freon

Question
The AC compressor for my '92 cadillac deville (75,000 miles)has gone bad.The system has never been serviced except for normal topping off with freon. A certified mechanic told me that it was a very expensive repair because one of the bolts holding the compressor cannot be removed without raising the engine to provide clearance for the wrench. I am thinking of doing this repair myself and I have the equipment to do this if necessary.

I want to convert the system to R134 and plan to buy a compressor designated for R134 conversion. The same mechanic told me that it was easy to flush the system using brake cleaner fluid and compressed air. Can you give me your opinion on these repairs?  

Answer
Hi Richard, I don't think very much of a "certified mechanic" that flushes out a/c systems with brake clean. That isn't what it is for. You can buy the propper flushing solution from the parts store and know that there won't be any side effects due to a chemical reaction between brakeclean and seals, oil , etc. If you have the 4.9L engine in your Deville there isn't any bolt that the engine has to be raised up to access in order to remove the compressor not that I have found. He is right on 1 point in that the R12 freon is at least $40 a pound and you would need between 2-3lbs and most likely be charged for 3lbs and that would be expensive. A/c compressors are shipped now without any oil so it doesn't matter what freon is installed. The problem is not all oils are compatable with R134A and the R12 oil is one of those. I was in Auto Zone the other day and they have a kit that claims to have all the fittings and oil to convert over so all you would need is the kit and freon. NO COMPRESSOR REQUIRED. Follow the directions on the package and it sounds like an easy job to do. The thing with R134A is you don't need as much to fill the system but the hose connections and seals need to seal and be made better than R12 because the 134a freon can leak past the smallest gap. That's my 2 cents worth. Bill