I have had the old leaky Schrader valve trick myself. I have several cans of R134 in the garage so I will go with that. How is ES-12A different? Don't know about it.

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red