I seem to remember having to remove the schrader valve from the low side port before putting the 134 adapter on. I know that the new adapter had a schrader valve already on it so this makes sense. I was looking at an adapter for the high side port and noticed that it does not have a schrader valve in it. I can't see how this would work. Can anyone clear this up?

 

Both high and low side valves on an R-12 system have Schraeder valves. The R-134 conversion valves thread directly on to the existing R-12 Schraeder valves. You do not remove the valve core on either one.

John

 

I am looking at the new adapters for 134. The low side has the valve already in it and the high side adapter is hollow. Is this correct or do I need a schrader valve in the high side adapter?

 

I think that is correct since the high side adapter is shorter whereby the gauge valve pin can reach down into the original schrader valve whereas the low side is taller and the pin of the manifold gauge valve won't reach the original schrader. Make sense? I'll verify that when I get home and can look at the adapter valves on an R-134 conversion.

John

 

REMOVE the schrader valve from the low side R12 fitting, the high R134 fitting will screw down over the R12 high side fitting and uses the existing schrader valve

 

I have done a little more research on this issue and have found out that there are two types of adapters for the low side. One type you remove the original schrader valve and the other type screws in over the existing schrader valve. The first type is an actual valve that seals itself just as the original schrader valve does. The second type has an extension needle that depresses the original schrader instead of an actual valve that seals. This type needs the original schrader in place since the extension does not actually seal. On the high side, all the adapters that I found were hollow. The explanation I got from various sources is as Jtmerritt states about the needle from the R-134 quick connect coupler being able to reach through the adapter and reaching the original schrader valve. This is still a theory because I have not yet found the quick connects that adapt my R-12 hoses to R-134 service ports.

 

dino360,

I did check the R-134 adapter valves that screw down on the R-12 schraders. Low side adapter has a schrader high side does not. I got them from Autozone when I did the conversion. Another thing you will find out about the R-134 hoses used with a gauge set is that they are self sealing. By that I mean as opposed to the R-12 hoses which are open to atmosphere, the R-134 hoses seal and will keep freon in them. Good feature in that it eliminates the need to have to bleed the hoses of air. However, even though the piercing valve seals tight to the can, I still bleed the hose to make sure there isn't any air in the hose from the valve to can connection. Probably my **** side showing through but I just don't want any air in my A/C system.

John