[Tom Kaiser]

I find the following sizes listed for Schrader valve cores:

Standard
8 mm
10 mm
GM high flow
JRA

Does anyone know which one of the above will be in the low pressure port? The system was converted in 2006 to R134a by a MB dealership. That is the limit of A/C system details that I can provide.

I plan to replace the valve core while under refrigerant pressure using an extractor designed for that purpose. I prefer to not begin removal and then find out I bought the wrong extractor.

Here is a Schrader Engineered Products Division document:

http://www.schraderinternational.co...rica/AC Valve Manual_User Guide_10-21-13.ashx

 

[liviu165]

I don't know the direct answer to your question, but if the system was converted by a MB dealer, chances are they all used the same core valves at that time, and perhaps still have them around. With that in mind, why don't you buy 1-2 core valves from your MB dealer and see if your tool can handle them.

I recently ran into the same issue, trying to change core valves from a F150, only to have the surprise that my tool could not handle the Ford core valves, so I could not change them.

In your case I suspect you'll find you have the "standard" version.

 

[Hector Varela]

Was just there last week.
My AC was converted at MB dealer also. (2014)
For the low side, they screwed on a 134 adapter containing a small plastic plunger that actuates the original core.
If you look into the adapter, you will see what appears to be an allen with a dot in the center.
This adapter can be unscrewed in order to access the original schrader. It is actually the same as used in the tire stem.
Be careful when removing adapter as not to loose tiny frigging plastic plunger thingie, you will need it again!

 

[liviu165]

For the low side, they screwed on a 134 adapter containing a small plastic plunger that actuates the original core.

If I understand it correctly and his setup is like yours, to replace the valve core he may actually need to replace the core in the original R12 valve and that will require a different adapter, which in turn is a totally ball game now.

 

[Tom Kaiser]

If I understand it correctly and his setup is like yours, to replace the valve core he may actually need to replace the core in the original R12 valve and that will require a different adapter, which in turn is a totally ball game now.

Liviu165 sums up my thoughts exactly. The input from Hector Valera makes this a whole new ball game.

Currently my system is holding the charge I put in Sunday. I will monitor the charge periodically before I get too carried away ordering tools that may not work. If I do lose pressure to the point of adversely effecting the cooling ability then I will stop at the local MB dealership and ask for their input.

Also, my Brother-In-Law has tools to remove the original R12 Schrader valve core without loosing refrigerant so removing the adapter may be my best choice. I won't try to remove the adapter until (and only if) my refrigerant pressure drops below minimum.

This is what makes the BenzWorld.Org Board so valuable! My thanks to All.

 

[Hector Varela]

I will take a picture tomorrow and post it.
Regular tire valve core tool is all that is required.

 

[Tom Kaiser]

I will take a picture tomorrow and post it.
Regular tire valve core tool is all that is required.

I took some pictures this evening and it appears that my R134a adapter uses a Schrader valve core instead of your small plastic plunger set-up. I suspect that if I remove the adapter I will lose all refrigerant. Tomorrow morning I will clean off all of the oily residue on and around the low pressure port.

 

[MBL87560SEC]

Hey Tom,

My '91 car has that exact same low side setup..

On mine, the 134 adapter apparently was screwed on over the R12 access port and in my case, and was ever so slightly loose, causing a slow leak. I snugged it up a tiny amount and that was that. I surmise it uses the standard sized schrader.. same as a tire stem..

You could as someone who has /uses a stem tool if you might use it in the adapter, [after cleaning of schmutz of course]. It will drop right on if I am correct.. if not, you'll still have your answer as to what valve to get...

Good luck man,

MBL