hey sms, I have not tried this product, but from what I've heard, this is they way to test or top off your R-12 system. Good luck
http://www.freeze12.com/
PLease let me know if it works
Regards,
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a2
1978 280 CE silver
1986 560 SL black
1987 300 SDL cream
1994 SL 500 brilliant green
1997 E 300d dessert silver
2005 FORD F250 Superduty Crew cab 4x4

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