Question for the old car guys...

[firebirdparts]

I apologize for the ugliness of this question: I don't know of any more reasonable place to ask.

In the late 70's, I guess, R-12 systems were "idiot proofed" with a smaller service connection on the high pressure side. Did this use a different Schraeder valve? You can buy one anywhere? I know it's crazy but I have 4 cars here with working a/c from that era. Generally they don't leak (much) with the cap on. I was just wondering if I could do better.

 

[Wrench97]

Yes you can still buy the service valves, ports and caps for R12 systems.

 

[65ranchero]

As I recall R12 gauge hook ups were the same size, could hook the lines up backwards. Had to be careful which side is low side for charging.
Some where around the early'80s the sizes were different
A little later sizes changed and then totally different for R134

 

[Wrench97]

As I recall R12 gauge hook ups were the same size, could hook the lines up backwards. Had to be careful which side is low side for charging.
Some where around the early'80s the sizes were different
A little later sizes changed and then totally different for R134

That changed in the 80's, the low side were standard HVAC ports the high change to several different designs depending on the manufacturer of the car.

 

[firebirdparts]

Okay so I feel pretty good about the high side in UAC parts VC-2903C. I can't figure out how to buy from them online. Talk to them monday, I guess.

They list cross-reference:

Four Seasons	26777
Global Parts Distributors	1311567
NAPA	801799
NAPA	801808
NAPA	TEM801799
NAPA	TEM801808
Omega	MT2903
Santech	MT2903
Trad Automotive	OTH364

In other news, I can't get the low pressure one out. I unscrewed it, but I didn't get it out. Not sure what to think about that. I may need to overcome some o-ring friction with some tweezers.

The smaller valves look like they'd fit a tire, but the seal is a little longer than a tire valve on the 40-year-old one I pulled out. People who sell this stuff don't really go into fitment much. using this list I see a lot of kits around with 4 of them, and evidently they must fit 134A cars, otherwise, they wouldn't be in stock everywhere. These kits have two bigger valves that fit something. Don't know what.

Anyway, evidently they must be common as dirt, the one I'm looking for. I'm just using ESP to figure out that if they're throwing in 6 different style caps, they must fit a lot of stuff.

 

[Wrench97]

What make and model car?

 

[Junkman]

In the 1960s they use brass hex caps with an "O" ring seal under the cap. Then they started making them from aluminum with a rubber seal under the cap. Next came a thin stamped aluminum sheet metal screw cap, and finally the plastic caps. I am primarily familiar with the GM product line, however, the Chrysler products of the 1960s is very similar. If you can find some of the older metal ones, those are the best.

 

[Wrench97]

The caps were never meant to be the seal on these.

 

[Carguy99]

As I recall ford had a different size for one of them…

 

[firebirdparts]

78 Firebird. I should have mentioned it's GM. I have multiples of the same car, actually, but of course they made many millions that are similar. Also have a couple of pre-R134a Fords.

 

[Wrench97]

The universal core kit should work, unless of course it has dissimilar metal corrosion issue that is stopping you from removing the core.
What is that stuck core in a hose or the accumulator?
You may want to see if you can get the orifice tube out while the system is discharged.

 

[Junkman]

I have a tool that allows you to replace the Schrader valve core without losing your charge. One use and it has paid for itself.

https://www.amazon.com/dp/B07T1PBD6T/?tag=atomicindus08-20

 

[Mr onetwo]

This kit at Autozone fits your car https://www.autozone.com/cooling-he...stem-valve-core-and-cap-kit-mt2903/947264_0_0