Replace air conditioner service charge port valve core and location

All air conditioner valve cores leak. They are only intended to hold the refrigerant in when you remove the charging station hoses until you screw on the caps. The caps have rubber o-rings that seal the port when you are done servicing the system.

I'm having a hard time following what you're saying. I never looked inside a port so I'm not familiar with the rod and ball you're referring to. I just charge the systems with the correct measured amount of refrigerant, then screw on the caps. The caps are what seals the ports. The valves just give you time to screw them on. They all leak a little which is why we never let a car go without those caps.

I get nervous when you're talking about removing a valve core because refrigerant is extremely dangerous to work with. It can cause blindness and frostbite. Mechanics wear gloves and safety glasses, and the smart ones wear a face shield.

I was confused too by your comment about a cold high-side line. The high side is where the refrigerant gets pumped into a high-pressure vapor and becomes very hot. It gets cold where a low pressure liquid turns to vapor, which is supposed to be in the evaporator in the dash. If the system is fully-charged and there is a place under the hood where a line is getting cold, that is the point of a restriction in that line.

I'm getting the feeling you're running into a problem common with GM vehicles for the past few decades. They like to design and build their cars with assemblies rather than individual parts. Examples include their generators and their distributors. Both were self-contained assemblies that were expected to be replaced as assemblies. They were not expected to be diagnosed and repaired. That came later with parts made available by aftermarket suppliers. The advantage to this was the cars went together on the assembly lines much faster, and the dealership mechanics didn't have to be trained in how the systems worked or were to be diagnosed. The disadvantage for car owners was they had to buy a complete generator when perhaps just the internal voltage regulator was all that was needed, or they had to buy a whole distributor when maybe the ignition module was the only bad part.

It sounds to me like you are expected to replace the entire hose if you want to replace the valve.

I explained how GM designs and builds their cars. They like it when you have to buy a very expensive assembly instead of a little part. When this is the case, the assembly is the only way you can get the part from the dealership.

It's the aftermarket industry that addresses this problem and makes the smaller parts available. If a valve core is available separately, you'll find them at a radiator repair shop or air conditioning shop. The people there will be able to tell you how to replace it.

If the valve IS available at the dealership, they will be able to tell you if a special tool is needed. You might also speak with their AC specialist in the repair shop. He might know of a special trick or procedure.