Automotive Air Conditioning Information Forum (Archives)

Drake57 on Fri February 22, 2013 3:03 PM

Refrigerant Type: R134A

I say so, but people I know have said that the dust cap is really the seal that keeps refrigerant captured.

My daughter's car leaked down quickly, it was the shrader valve, I replace the hose assembly, fixed the leak.

Can anyone tell me the truth? I think a tight seal is required of the S valve.

Thanks, Drake.

Drake57 on Fri February 22, 2013 3:04 PM

Moderator, please delete this inadvertent duplicate post, thank you.

Z2TT on Fri February 22, 2013 6:57 PM

To be honest, Not really.

If the valve cap has a good seal, this should stop any leaks. So long as the plastic material on the cap
can withstand 100+ PSI without cracking.

But best practice would be to fix the source of the leak, a swell as have a good valve cap on there.


Edited: Fri February 22, 2013 at 6:59 PM by Z2TT

NickD on Sun March 03, 2013 1:57 PM

Decided to clean my 1991 Amana refrigerator condenser plus oil and clean the fan. This is not the first time, do this quite frequently, but never noticed that this refrigerator actually has R-12 Scharder valve ports on it, yes the refrigerant used is R-12. Really has a beautiful set of brass caps on those ports, made a note, if I ever toss this refrigerator, to save those caps.

Still working great after 22 years, and the R-12 capacity is only 4.75 ounces, so those caps must be good.

iceman2555 on Sun March 03, 2013 2:10 PM

The primary seal is the schrader valve...not the cap. One of the major areas of leakage is the schrader valve. It is suggested to replace this valve/assembly during major AC repairs.


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Thomas Jefferson

AutoCool on Mon March 04, 2013 3:40 AM

Iceman is correct. The service port cap is usually just thin plastic with just a few threads, often there isn't even an oring or gasket inside for sealing. I think a better name for that cap would be dust cover. I've seen quite a few cars here in Sweden that have refrigerant lines running under the car and also have service ports on those lines. They often collect road salt and the port as well as the schrader valve get corroded.

If the cap can't even keep road salt from corroding the interior of the service port, there is no way the cap is going to keep refrigerant from escaping under pressure.

"Primary seal" is the name used for the replaceable metal ports that contain a sealing valve.

There actually was a better cap system used by Volvo during the R-12 to R-134a transition period, but the port fitting size and form was not accepted as the industry standard. You can see these on some Volvos from 1992 that were built in 1991. Some cars came with R-12 and some with R-134a, but their port system was in place. Here's a picture of what they look like with the cap in place and removed.



Edited: Mon March 04, 2013 at 3:45 AM by AutoCool

NickD on Mon March 04, 2013 8:28 AM

Found fancy chrome plated neoprene gasketed tire valve caps for my car and bike tires at Fleet Farm, a set of four for a $1.99. Just on the basis that two seals are better than one, plus they double to keep that road salt out of those Scharder valves.

Would think with all this EPA BS, such caps would also be available for MVAC applications instead of those cheapass plastic caps.

Just because only these brittle stupid MVAC plastic caps are available, doesn't make it right. Can also state after doing this for some odd 50 years now, those Scharder valves are far superior to these stupid R-134a ports, just more problems. Another reason why I feel the EPA is loaded with complete idiots.

Cussboy on Thu March 07, 2013 1:30 PM

Quote
Originally posted by: NickD
Decided to clean my 1991 Amana refrigerator condenser plus oil and clean the fan. This is not the first time, do this quite frequently, but never noticed that this refrigerator actually has R-12 Scharder valve ports on it, yes the refrigerant used is R-12. Really has a beautiful set of brass caps on those ports, made a note, if I ever toss this refrigerator, to save those caps.
Still working great after 22 years, and the R-12 capacity is only 4.75 ounces, so those caps must be good.

Funny, reminded me of the early 1980s when my late 1960s refrigerator started getting warmer. I added a partial can of R-12, it had the valves, worked great. A month later, started warming up again. This time I noticed that the refrigerator's cap had a rubber seal inside that was broken, so I again added R-12, went out and got a replacement cap, and BINGO - it was fixed good !!!

NickD on Fri March 08, 2013 8:01 AM

Even have that tool for changing a 75 cent Scharder valve without discharging the system. Are we talking about the good old days?