JUST purchased a set of 134A a/c gauges from local parts store. there is a blue and red for high and vacuum side. But there is also a yellow one ???? Now basing on the fitting, there is a valve that automatically shuts when not connected, so I'm assuming that that's where the refrigerant bottle goes. Any thoughts?

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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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