Does any one know of a source for metal caps for R134 service ports ?
It kind of strikes me as ironic that the r12 systems had metal caps that would seal a leaking Schrader valve but the greenies when forcing the 134 on us chose plastic caps that would likely allow a leak by

The caps are only designed to seal dirt/moisture out not seal a leaking Schrader valve off.

I knew that but if the valve was leaking a metal cap would stand a much better chance of sealing and not contributing to OMG Global warming. I mean isn't that why R134 is going away or is it a, well the scam worked last time so lets do it again LOL

It wasn't a scam, And if you are worried about leakage replace your old valves. Never had a issue with them.

what about putting a small o-ring [that just fits] inside the cap ?
or use a leather punch to make a gasket out of an old inner tube [using the "hole" piece created by the punch] ?
that may seal the cap to the fitting somewhat.
just tossing something out there.

OK
But 30 years ago R134 was the solution, Now it is deemed harmful once again Using metal caps with seals would've provided secondary containment for a refrigerant that is now being replaced due to it's effects on the environment.
Sounds too familiar to me
I have my own theories on global warming and it has little to do with freon

Most of the caps do have a Silicone/Viton/rubber type seal but the caps being plastic and exposed to heat were a poor choice IMO.
I've found some slip over covers but I was curious if anyone knew of a source for metal caps

I'd guess the primary reason for going to plastic caps was to cut costs! Manufacturers LOVE to cut costs and then give some other "reason" (or excuse!) for what they did. They do not want their customers to think they are manufacturing a "cheap" product. A corporation's primary focus is always on increasing profits, regardless of what their PR department claims.

Always remember the saying, "Follow the money." The money will usually lead to the truth!

Nailed it on the caps and new freon IMO

Never seen metal caps for 134 but then I never seen a failure with the plastic ones in over 35 years

Gus

These claim to have"leakproof hat's" doubt you will find metal ones.
https://www.amazon.com/Conditioning-Charging-Leakproof-Pressure-Pressure10pc/dp/B07VCJ561V

thanks but I'm not sure I believe those would be any better than other "plastic" caps