Did you convert with cheapie charge kit, or go the whole 9 yards with a proper conversion? It seems that these cars are capable of decent AC with r134a if care is taken with the conversion.

If you want your AC to work a lot longer, get the system tested for leaks. Have the shop evacuate it when done testing and order the parts necessary to seal the system, along with a Volvo conversion kit. Get compressor o-rings too, you will want to remove it to dump the oil. Get the system tight with the new receiver-dryer. Take it to a shop, have them draw down a vacuum for about an hour and check afterwards if it holds. Then fill with r134a again, to approx 85% of the R12 capacity. The shop may also fill by a combination of AC performance and high side pressure.

This way you will have the cheap, standard gas in the system without having to worry about mixing lubricants and black death caused by goop in the system.

AC shops online sell aerosol spray flush kits. FCPgroton.com has the AC conversion kit for a reasonable price. Aftermarket condensors are on e-bay as are hoses. Brand new compressors from places like nostalgicair.com are surprisingly affordable.

Good luck!
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Herb Goltz, Aurora, Ontario, Canada '92 245 w/130K mi, '92 945T w/200K mi