I have a 1984 240 with a York compressor. Four years ago I converted it to R134. It has worked great once I got the worthless rebuilt York Compressor problem worked out. Now it is not cooling as well as it used to. I checked the pressures and they are 22lb low side and 210lb high side at 1800rpm at about 85 degrees outside temp. The duct temp is 50 degrees. I live at 7000 feet above sea level. It seems to me that it used to run at 190lb high side and the duct temp would go below 40 degrees. This is after I filled the system up with R134 until the bubbles just disappeared in the sight glass. I know it needs a little more R134 to be topped up but it seems that the high side pressure is too high. An a/c tech told me I could put more R134 in to bring the high side pressure up to 250lb and the low side to 30lb and this would be the right pressure s for the system but I am worried about blowing out the front compressor seal. Does any one have any experience with this?