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Is schrader valve what seals in

Drake57 on Thu February 07, 2013 6:11 PM User is offline

Refrigerant Type: r134a

the refrigerant, or is the cap the primary seal? I've heard different ideas about this. In my view, a tight seal at S valve is required, and the cap is to keep dirt out.

Others say the S valve is just to give tech time to get the cap on and the cap does the sealing - this contradicts my experience, daughter's 95 contour was leaking it's refrigerant from high pressure charge port S valve, I replaced the hose/S valve assembly, cured the leak.

Thanks, Drake.

GM Tech on Thu February 07, 2013 7:28 PM User is offline

I used to think the shrader was most important- but every valve that holds in a charge without a cap leaks-- I use them to test my sniffer- you can blow them out with an air gun and 10 seconds later put your sniffer to the shrader and your sniffer is going off. So you be the judge. We use to do experimental work with numerous valve (pressure taps) through out a system- if we did not use a transducer on a given port- we would just block it off with a plastic cap (with a good rubber element inside) and continue testing. You prove to yourself- there is no leak by sniffing it with your best leak detector.

Plus I once had a nice long conversation with a hose designer- he will tell you that the shrader valve is there to give you time to put the primary seal- (the cap) on.

Forget what anyone says- prove it to yourself- sniff your capless port and let that be your answer. That's what I did 20 years ago.

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

NickD on Fri February 08, 2013 8:23 AM User is offline

Scharder valve is far superior for sealing and far easier to replace, plus they were also using metal caps with neoprene seals inside. So then the EPA comes along moaning about leaks. Use that stupid quick coupler with a disc that can move around, does wear a groove in that disc, if it doesn't center perfectly, will have leaks.

If this isn't bad enough, goodbye metal caps, hello plastic ones, if tightened a tad too much will crack in your fingers. With age and heat, particularly on the high side, that plastic becomes very brittle.

Take up these issues with the EPA.

For years could use my same gauges for both R-22 and R-12 until the EPA comes along with a ton of different refrigerants where each needs its own unique ports. Just created a huge market for adapters, and if made in China, more crap, and even more leaks.

While less than 2% of the total CFC production is used for MVAC applications, treating that like its 10,000%. Approved using propane in spray cans any two year kid can get a hold of, but disapproved for MVAC use, even by professionals. Then comes along environmentally friendly HFC's now causing global warming. In around 1976, trichloroethane was banned by the EPA, but gave DuPont the okay to use it for the production of R-134a.

What a bunch of idiots making our laws, but have to follow them or end up in prison.

Keep a stockpile of those red or blue plastic caps on your shelve, they are good for about a year.

Cussboy on Mon February 11, 2013 1:31 PM User is offline

My 1984 Jeep Cherokee V6 (R-12, naturally) had a compressor with the manual shut off valves, used a 1/4 inch square socket to turn them.

If I remember correctly, it only had dust caps over the threaded flare fittings. It had no shraeders.

NickD on Tue February 12, 2013 9:24 AM User is offline

Must be like a York, have one of those too. Not really much happens by connecting the manifold gauges to the ports with those valves closed.

With no EPA back then, it was like they cared about leaks, ceramic compressor seals, brass evaporators and condensers, and who even cared when a can of R-12 was 25 cents. Could even more the compressor aside without discharging the system when pulling an engine. Today, have to recover to remove a compressor just to change a spark plug on some vehicles.

Seems like the EPA wants us to have leaks, so they can catch us getting rid of that last ounce hitting us with a $25,000 fine. But the way they are made today, won't even find that last ounce in the system. EPA has no jurisdiction over the OE's, just picking on techs.

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