I agree about the white mist. Mine does that sometimes when I first turn it on. The constant cycling when there is enough pressure might be a sign of a widened condensor clutch gap. It can be lessened by removing some shims...usually done from under the car. I've read about it but don't know the exact procedure, but if you do a search you're bound to find how to measure it as well as how to alter it. Good luck! Personally, I'd add some R134-A as long as you don't go over 40psi when the system is on. Are you checking with the A/C on? Otherwise you won't be getting a correct reading.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.