Air Condition Service Ports Valve Core Sizes
 

I need to replace a leaking valve core on the high side AC service port of my 99 W163 and was looking to find out the correct size/type valve core that I will need to order for a R134a system. Existing hi-side valve has a smallish leak and will use one of those valve core installers that allows to swap out the old and new valve cores without loosing the system charge. I did already try "bliping" the valve to clear any debris that might be causing the seal not to be seating properly, but that did not help.

Has anybody done this job on their MB car and could please give me a hint as to where I could get the right valve cores for both the High and Low side ports? I am not in the US, so can't unfortunately use any walk-in store recommendations as I will need to be able to order online instead.

Looking at ebay plenty of those valve core installer tools available and some even do include a small assortment of valve cores. However no way to know if any of the included cores are going to be the right fit until after I have removed the existing leaky core. So would be nice to be sure even if I have to order the correct cores separately.

Thanks in advance for any leads.

as far as I know the valve for AC systems are an industry wide standard. The old R12 system was a bit bigger. I have a vacume pump for charging R134 AC systems and it only came with one size to screw into all systems. I have used it on VW, Ford, Chevy. All the same size. I do not even know if it is the high side that is bigger to the low pressure side off the top of my head. One fits the high side and one fits the low side. So the valve you get should be the right one as long as you do not get a set for the old R12 system.

Hi, you are talking about the ports correct? Well the fittings itself are obviously the same for most if not all cars as one recharge hose fits all, and the low side port is somewhat bigger than the high side port, mainly due to the size of the pipes.

But just to clarify, what I was asking is the size of the valve cores that go inside the ports, not the size of the ports itself.

Thanks all the same.

Pull one from an unused tire and test fit or a propane canister. I think they are mostly the same as far as fitment and thread

the tire and ac valves are not interchangeable. schrader says so. i know it's a test but they say they are different.

Have you tried tightening first?

I notice my valves need a little tweak every few years. I pick up a slow leak with my halide detector and I can stop it by tightening the cores a tiny bit. The ones I have use rubber seals and I guess they just creep over several years

ETA also I’ve noticed there is varying quality in cores. The ones I’ve received with fitting kits on eBay have tended to develop leaks faster than those I buy from the shelf at Autozone…I think the brand is something like AC Pro. Their cheap but they aren’t bottom of the bucket like the ones that come in free with the schrader tool I order direct from China.

I think will order a valve core removal/install tool from ebay and give it a try to just tighten the leaking core. You might be right.

But it is quite disconcerting that it seems to be impossible to find out the size of those valve cores, or even any reference at all, and even less any MB part number.

I wonder how are the AC shops dealing with this when doing work that requires valve core replacement on older late 90s MB cars. One size fits all?

Ordered this set that also includes an assortment of valve cores. Maybe I'll get lucky and some or at least one of them will be MB compatible.

https://www.ebay.com/itm/296334057653