Originally Posted by TQ60
If upgrading to r134 one uses about 80% but that is just what some instruction sheets indicate.
I have charged via glass and manifold and instructions indicated some bubbles okay and manifold close.
Would like some comments from pros who have done so many they can do it in their sleep...
You are correct 134 uses less the 12. If you are changing to 134 from 12 clean the system with a flush then back blow filtered air vacuum system down. Then install new receiver dryer and oil if you are keeping same com pressure. Then service with about 80% 134. Top as needed. Some say you have to replace the hoses and compressor but you do not. Once the hoses is harden they will be fine.
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