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High Side Gage Fitting Question

Mr_Squishy on Thu July 08, 2010 5:41 PM User is offlineView users profile

Year: 1986
Make: BMW
Model: 635CSi
Engine Size: 3.5L
Refrigerant Type: R134a
Country of Origin: United States


I've looked around and cannot seem to find an answer for this.

My gages have R12 connectors and R134a adapters. I just rebuilt the whole AC system. Converting from R12 to r134a as system failed before I bought the car. New evaporator, PF condenser, drier, pressure switch, expansion valve, and all new hoses. Flushed (what was left) and vacuumed.

Low side hook up is obvious and works fine. I have a R134a adapter in my new low side hose. I can hook up the high side directly without an adapter using the R12 fitting on the new drier. (The drier is sold as R12/R134a.)

Removing the high pressure is ugly. I lost some refrigerant and oil when I removed the hose. Probably not the end of the world, but it bothered me as everything else worked great. I just realized I probably just need (in retrospect was obligated...) to convert the drier to an R134a fitting. I forgot about that in my rush to "make it cold again". An adapter fitting will probably solve my problem for now.

My lingering question is how would you remove the hose from the R12 adapters without losing oil and refrigerant? I am curious as I may end up converting back at some point.


ACProf on Thu July 08, 2010 6:37 PM User is offline

Before removing the high side connection, wait about 5 minutes after you turn OFF the A/C for the pressures in the system to equalize and bring down the high side pressure to static pressure. THEN remove the high side connection.

Its much easier (and safer) to remove the high side connector when the pressure in the line has equalized down to less than 100 then trying to remove the connector when the pressure in the line is still at 250! You could also spray the condenser with a water mist to speed up the process. I use a rag around the connector to protect from overspray and turn it off as fast as I can.

Mr_Squishy on Thu July 08, 2010 7:28 PM User is offlineView users profile

Thanks for the reply.

I actually waited a while as engine bay was pretty hot and the receiver/drier area is cramped.
There was just more released than I expected - maybe I was just too slow turning the fitting

mk378 on Thu July 08, 2010 8:34 PM User is offline

Premium R-12 gauge hoses have self-closing fittings that reduce this problem.

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