The last thing you want to do with a 134 system is OVER charge it. If the performance is marginal, that may very well be your problem.

Find a Factory Service Manual for this specific car and it will have a table of vent temps vs. ambient temp. That will let you properly evaluate the system.

The best way to charge an evacuated system is by weight. Preferably a charging scale which will tell you exactly what weight you have removed from the container. Failing that, calculating the number of ounces and filling with that much from cans. Like say for 40 ounces, put in 3, 12 ounce cans a little of the last one. Since the system has no accumulator, it is best to err SLIGHTLY on the too little side, rather than too much.

Hope this helps.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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