I want to recharge the refrigerant in my auto air conditioner. I've
assembled all the necessary tools except for one item. My vacuum pump
is outfitted with a 3/4" female NPT fitting and the discharge tube
from the gauge set is a R134a female fitting. I plan on machining an
adapter to get the 2 fittings connected to each other.
But I can't figure out what the thread size is on the R134a. Please
Don't reinvent the wheel by machining the fittings, it's silly to
waste $100 to $200 of your time on a $5 part - you only do that when
it's made out of pure Unobtanium... Go to any refrigeration supply
house or search online.
They have in-stock adapters to go from NPT pipe thread to 1/4" SAE
Flare (HVAC and Refrigeration charging hose fittings) 3/8" SAE Flare
(manifold to vacuum pump hose connection) and 1/2" Acme Flare (R-134a
Automotive Manifold hose fittings)
Your vacuum pump should have 1/4" SAE Flare and 3/8" SAE Flare
fittings if it was made for refrigeration work - you connect the
manifold hose with the 3/8 fitting, and can attach the micron vacuum
gauge to the 1/4" to monitor your progress.
(If the system under vacuum has an extra service port, connect the
vacuum gauge sensor directly to it. That way you can isolate the
system with a ball valve and shut off the vacuum pump, and monitor the
vacuum levels for leaks and/or trapped moisture still evaporating from
the refrigeration oil.
If you are adapting an industrial vacuum pump, you'll have to
bushing down from 3/4" NPT down to the threads needed for the adapter.
--<< Bruce >>--
On Sun, 14 Jun 2009 23:59:03 -0500, Richard J Kinch
What the (heck) are you talking about? They don't have to be
Unless they've made some serious changes since I took and passed the
test, there are no approvals processes or "lists of approved
machinery..." You just have to use procedures to reduce accidental or
incidental release of CFC's and HCFC's as much as possible. And
deliberate release is instant trouble.
A car using R-134a is running an HFC. No chlorine.
--<< Bruce >>--
The EPA via the Clean Air Act regulates what fittings can be used with what
refrigerants. Not the marketplace, not engineering standards, not the
convenience or expedience of you or me or the OP. I don't agree with the
despotism of the government, I'm just warning you. The law makes us all
criminals, even for things like cutting metal. The tender mercies of the
bureaucrats decide who is punished and who is given lenience.
On Tue, 16 Jun 2009 02:40:58 -0500, Richard J Kinch
The service fittings permanently installed on the vehicle or
stationary system, yes. If you do a conversion from R12 to R134a or
another refrigerant you have to change the fittings to the proper
style to avoid accidentally mixing refrigerants.
But not an adapter made so you can hook up your service manifold
hoses to the car or refrigerator being serviced, or hook up the hose
from your vacuum pump to your service manifold. They may be stupid
MF's working for the government, but they ain't THAT stupid.
It's the mouth breathing politicians who wrote the impossible to
follow laws the bureaucrats are trying to (selectively) enforce who
*are* that stupid. Which is why politicians are like diapers - they
need to be changed often, and for the same reasons.
--<< Bruce >>--
The EPA holds that if certain fittings are required, then adapters to
circumvent them are not permitted, since that defeats the very purpose of
the fittings, namely to make impossible the mixing or confusing of
refrigerants. While the utility of adapters is obvious, you're supposed to
have a separate set of gages and hoses for each refrigerant. That's the
governmental logic: intelligent economizing must give way to backstopping
As Uncle Al sez, environmentalism is expensive, shoddy, and deadly.
On Wednesday, June 17, 2009 at 3:16:09 AM UTC-4, Richard J Kinch wrote:
So ..leave those fittings for R134a on your hoses because they are not adaptors, but a permanent conversion to make an obsolete tool usable. If it became necessary to permanently convert the tool to R12, do so at that time.
True, It is a shame that the Constitution was written by folks who felt
that serving in government was such a PIA that nobody would WANT to do
it. Term limits were not considered because of that.
I'd like to see term limits for ALL elected offices. Never going to
The founders all had things to do, like managing a business.
Government duties detracted from that.
I sure wish the people in Washington DC had other things to do.
Idle hands truly are the devils workshop
Well we noticed this really old thread and see that it still gets lots of hits on Google. So if anyone is still looking...
Gary: "But I can't figure out what the thread size is on the R134a. Please
I grabbed a bolt and checked if it screws in to the R134a in or out. It fits.
1/4" - 24
Meaning a 1/4" diameter bolt with 24 threads per inch (fine thread)
Someone should confirm this.... but does that help anyone?
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