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Converting from an R12 A/C System

Converting an R12 A/C system to something else similar to R134a I took a look at the site and the data I'm still a little skeptical. I'm no expert on the subject by any means - I have enough experience to be dangerous - but some of their claims don't seem to hold up. Like that it is compatible with the existing oils, but in their installation instructions they require at least 2 oz of POE on top of the existing mineral oil. And they recommend draining the mineral oil from a replacement compressor and replacing it with POE. Sounds like the product may NOT be compatible with mineral oils...

It sounds like FR-12 is a blended product. My experience with blended products to replace R-12 has been pretty bad. After testing several different R-12 "replacements", we went with a product from a major manufacturer of CFCs that was marketed as a Class II direct replacement for R-12 in some temperature control units we supplied as part of our equipment. It was a blend of R22, R134a, and R62 if I remember right. Initial the stuff worked great, but over a period of time (6 months), the performance dropped off until it reached the point were the systems would no longer work, usually causing compressor failure. Turns out that the different diffusion rates of the three refrigerants caused over a period of time the composition of the refrigerant to change, radically changing the it's performance. We couldn't find any seal or hose material that would give us uniform diffusion for all three refrigerants. This particular product was also very sensitive to overcharging. Even 1/2 oz over in a 22 oz system was enough for it to stop working properly. So we checked with the other "replacement" manufacturers and when pressed they all said that they were seeing the same type of diffusion problems with their products. The whole fiasco cost the company a couple hundred thousand dollars to replace the units with properly designed R-134a units.

FWIW, we had to change three things to get the units to work properly with R-134a: We went to the next size larger compressor (R-134a isn't as efficient), change to a POE oil (not compatible with mineral oils), and went to nylon belted hoses (reduces the diffusion rate).

red_triangle.gif (202 bytes) Comments by Jarrod K. Wright

Steve at Courtesy Nissan in Dallas got back to me today with a list of parts they replace when converting from Freon to R134a:

> OK, we have three part numbers from Nissan to make the retro kit:
> 27030-65Y05 is the main kit that includes o'rings, new warning
>                           labels, some covers, a pressure relief valve,
>                           receiver dryer, and expansion valve. List $168.00
>                           cost $126.00.
> 92442-64C03 A/C line-front. List $38.27, cost $28.70.
> KLH00-PAGR1 New fluid. List $26.63, cost $19.97.
> Total $174.67

I assume the rest of the $495 installed price is labor (except for the $5 worth of R134a). I suppose you could have your A/C system bled down and the Freon recycled at a shop, then install the parts yourself and bring it back in to add oil and recharge it with R134a. But for an operation as tricky and foreign as this, I'd gladly pay Courtesy or another professional to take care of it. :) I can see my compressor blowing itself into itsy bitsy pieces at startup, then watching in horror as that $174.67 turns into $1740.67...