Speedtoys

Is an R12 fitting the same as a valve on a tire?

Need to find leaks in a friends system with a nitrogen bottle..is it the same or does it require an adaptor?

Mikebte

I remember it being the same size, of course the schrader valve seal is different.
I have seen a few that were different, but I think it was on a semi and it had the same valve with the option on a different clamping style.

wpgshark

R12 had the same schradder valves as residential AC units, when autos went to R134 the access ports were changed. Amazon sells all manner of adapter to go back and forth.

Speedtoys

Ok..so a normal tire valve will fit/full R12. Thanks.

Rob Edwards

That's not correct, the R12 valve is bigger- I get .429" OD, measured on the outer threads of an R12 fitting, vs. 0.303" on a bike tire schrader valve.



EDIT: It's a bit of a kludge to go from a nitrogen regulator to an R12 hose, but doable- if this is the setup you're after, holler and I'll take apart the stack of adapters and measure.

griffiths

Speed,

As Bob pointed out, the diameter of the thread on a common tire schrader valve is not the same as an R12 service port's diameter.

There are 2 different size threads you come across on R12 service ports in automotive applications. 7/16"-20 and 3/8"-24. Grab your micrometer and thread gauges.

Usually what you do is find 'service hose' from an old R12 service set and adapt that to your regulator.

And, in terms of pressure, a typical auto system can run as high as 350 psi on the high side on a bad day, however don't pressure test it above 400.

Ideally, the best way to find a leak is with a refrigerant sniffer. Black light and dye methods are only good if you can see the area where the leak is. And, pressurizing with nitrogen limits you to same (whether you are using a liquid to locate bubbles or listening for the leak).

Griffiths Tech

dr bob

Jeff--

I bought a male tube thread by 1/4" female pipe thread adapter in the brass bits section at H-D to adapt my industrial-strength vacuum pump to a R12 service hose. The taper isn't perfect, but the hose has a tiny rubber donut seal that makes it work. It was a few bucks. Take your service hose with you. Remember when you use it that there's a little depressor in one end of the service hose. That opens the Schraeder valve in the charge port. Be Sure To Install New Schraeder Valves, even if you don't swap refrigerants. The little rubber seals in those originals deteriorate as fast as the o-rings in the joints, so new HNBR-sealed Schraeder valves are a big help.

griffiths

Here ya go, $9.07 for the hose assembly you need on Amazon with prime account:
Hose Assembly

Usually the service end (vehicle end) of the hose will have the pin Bob mentioned.
If not, simply remove the schrader valve core from the port you are testing.