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R-134a Conversions facts and fiction[700/86] posted by Tim Messenger on
Wednesday, 18 April 2001, at 9:12 p.m.
I've been looking into retrofitting my 740 to R 134a, I spoke with a local shop who as converted a few of a friends Mercedes and claims to have converted about 100 other cars, this was his advice: Don't flush the compressor when I've flushed compressors they've seized up so I just leave them alone. I don't replace o-rings unless I disturbed a fitting. Have a look at this article from EPA regarding 134a conversions, thier guidelines seem to match what he is saying. If your system is flat or leaking you may have corrosion around o-rings or other problems which would require attention but if not then changing the receiver, pulling the system down and re-charging with 134a may be all that's required.
Written by EPA's Stratospheric Protection Division
Last updated on January 8, 1998
http://www.epa.gov/ozone/title6/609/retrguid.html
Tim
Re: R-134a Conversions facts and fiction[700/86] posted by Steve Ringlee on
Wednesday, 18 April 2001, at 10:34 p.m.
Volvo has done much work on this and has a very inexpensive retrofit kit with complete instructions for all 200/700/900 cars. Any dealer can obtain this. It is definitely worth using the OEM retrofit kit and not putzing around trying to do it on your own.
Re: R-134a Conversions facts and fiction[700/86] posted by disco stu on
Thursday, 19 April 2001, at 7:14 a.m.
I want to strongly agree with this.
The Volvo kit is based on their knowledge of their own systems. It comes with everything that you need, except for refrigerant. You have to dump the old compressor oil out, but they do not call for flushing the compressor or the system.
Additionally, Volvo's kit is inexpensive, making it even better. You know you're getting the right parts.
One last thing is that you sometimes need a supplemental kit for the 740 series, although that also is inexpensive.
--disco stu likes RWD Volvos.
Re: R-134a Conversions facts and fiction[700/86] posted by Tim Messenger on
Sunday, 22 April 2001, at 11:07 a.m.
I agree 100%. I've read many posts on the conversion and they are all over the spectrum. I believe that "your old oil will wreak havoc" is just a myth. Most 134a oils are compatible with the mineral oils. The EPA article was helpful and it closely matches my experience.
- Ester oil is compatible with mineral oil PAG is not.
I had my condensor blown in a freaky way -- the rubber duct that leads to the airbox rubbed a hole in the metal pipe. I guess 11 years of rubbing is enough even for the metal pipe. I had my condensor fixed and I used Volvo conversion kit for new receiver/drier, orifice tube, and oil.
- The aluminum used for auto AC is very soft, it's a trade off, tempered aluminum would not erode but would be difficult to make tight bends and would crack from vibration. This is a heads up for owners of older cars, my car has an erosion in the high pressure line from being rubbed by a wire coming off the alternator ( plastic cover on the wire still looks perfect ) even things like zip ties will eventually erode the aluminum until it fails.
I drained the compressor but I squeezed only a few drops from it. It was
definitely not worth the hassle and I don't think I would bother with it
again. I replaced O-rings only in the fittings I opened. No system flushing, just evacuate and recharge.
- I've had the same experience when pulling compressors on older cars, I believe most of the oil is trapped in the accumulator and the lubrication of the compressor relies on the solubility of the oil with the refrigerant to carry it around.
This was two years ago and I have not touched the system since. The system
performance is slightly worse than R12 (as expected) and I have not observed performance degradation (living in Dallas, TX gave me plenty of
opportunities to observe).
I would not mess with working R12 system but if you have to open it for
repair, it's worth doing it.
Peter ('89 740 234F 205k)
Tim ( 86 740 230F 162k)