Quote:
Originally Posted by Dynomite
The 95 ZR-1s have 134 AC. I do not notice any difference as I have both 90s and a 95. You can get as much R12 on Ebay as you want for about $30 a can.
There are lots of stories and recommendations for the R12 to R134 Conversion.....both some negative and positive. I think the AC Compressor operates at a higher pressure with R134 for example but you would use the existing R12 compressor with R134. I just seen you are changing compressors anyway.
There exists several R12 to R134 Conversion Kits. First thing you have to do is vacuum out the existing R12 System.
I may do this conversion myself with a 1993 Ford XLT.....let us know how it goes  |
Quote:
Originally Posted by RICHARD TILL
I`ve converted no less than 25 cars to R-134. Its better to vacuum the system but not mandatory. Add one can of 134 to keep the compressor energized, then add the correct amount of oil. Now add 134 until the low side gauge reads 40-45 lbs. The compressor or dryer does not have to be changed.
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Seems to be some dubious information in this thread. I do HVAC work for a living and am licensed to do it. I convert, repair, etc. vehicles on the side.
The only r134 specific compressors are those that came on vehicles that were originally r134. Obviously there are some vehicles that were crossover years where one might exist in the same style and fit both systems. The only difference when you buy a compressor for an r12 vehicle labeled for r134 is the oil in it.
If you're not flushing and replacing everything, make sure you get an oil that is compatible with the old and new, not a 134 specific oil.
When switching a system over, the ideal way to do it is to flush the system with a cleaner, replace the drier/accumulator, change the orifice valve if it's not integral with the drier/accumulator, refill with the proper oil, vacuum the system down, then refill with r134 to the recommended percentage. Typically around 80% of the original r12 charge.
As far as changes between r12 and r134, the only thing that can be purchased that is specific is a new orifice valve and oil. It doesn't have to be changed, but the r134 designs are suppose to work better in retrofits. I've never noticed a real difference, but I'm sure it depends on the system and vehicle. These are typically integrated into the hard line with the accumulator/drier.
R134 put back into an r12 system will never be as cold. That's just the physics of it. The difference may not be noticeable, but they system was designed around the operating pressures and characteristics of a certain refrigerant.
I don't know how you would convert without pulling a vacuum on the system. You're either starting with a system that has no leaks and contains refrigerant and you'll have a mix, or you have a system that had a leak, contains air, and worse than that moisture. Part of the importance of the vacuum process is that it boils off all the moisture in the system. Obviously if there is air in the system, you will never get the proper quantity of refrigerant in. With digital gauges you should be able to pull an all original system with no leaks down to about 1100 microns. A new system should get down to about 600 microns. Anything way off from that has a leak or a lot of moisture.
A system that wasn't vacuumed will absolutely fail before a system that was. I would compare doing that to installing new wheel bearings in something without greasing them. They will be nicer than a bad bearing, but not as nice as a new greased bearing....and only for a short period of time.