I am rebuilding the AC system on my 66 300HP roadster and have been advised that the new "barrier hoses" suitable for 134a freon will not work satisfactorily with the OEM type barbed fittings and hose clamps. I obviously want to maintain the original look thus the hose clamps and "barrier" hose is all I have been able to locate. The AC shop advises that the barbed fittings will cut the liner in the barrier hose and since the 134a operates at higher pressures they will leak. Any experiences out there with this set up??
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Re: C2 Air Conditioning 134a and hose clamps
Randy,
I had 134 in my 65 for one year. I used everything (hoses, clamps, and fittings) for R-12 from Long Island. It worked ok but I went back to R-12 and gained 8-10 degrees. To put 134 in with the R-12 fittings I had old kits designed to use with the small (12-16 ounce) cans and adapted them to the kits you can but now for 134. Also I have a friend with a vacuum pump to evacuate the system before charging. The system looked very correct. This probably would not work if you are taking it to a shop for charging. Don H. -
Re: C2 Air Conditioning 134a and hose clamps
Don,
Thanks for the input. Do you know if the hoses from LI Corvette were barrier hoses ( with a plastic liner on the inside of the hose). Did you have leaks at the hose fittings? I would use R12 once I knew the system wasn't going to leak. I've been thinking of running r134 for a year to be sure everthing is going OK then switch to R12. Supposedly R134a needs the barrier hose to prevent leaks thru the more porous rubber.Comment
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Re: C2 Air Conditioning 134a and hose clamps
You can check your system for leaks before you fill it by vacuuming. Put a vacuum on it and hold it for a long time.Comment
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Disagree....
One chapter member is a pro HVAC contractor. We've 'recovered' MANY tuckered out AC optioned Corvettes over the years and have probably seen just about every quirk along the way.... Here's some advice:
(1) Yes, R134 requires 'lined' hoses due to relative molecular size of the refrigerant compared to R-12.
(2) Use of lined hoses 'can' defy attachment to some of the factory original R-12 based fittings. This could be important if the end objective is a factory concours 'correct' appearing installation.
(3) Pulling vac on a system that's been open/exposed to the atmosphere for some period of time is NOT equivalent to filling it with refigerant and exercising it in terms of seal integrity evaluation!
(4) Internal gaskets, grommets, valves can behave differently based on whether you're suckin' 'em in or expanding 'em outward....
(5) STRONGLY suggest 'gutting' the plumbing and replacing each/every seal as well as all four Schrader valves using the best refrigerant grade replacements money can buy. This is a MINOR expense issue (perhaps another whole $25 for the system). Most leaks happen at interface points and when a system's been sitting open to the atmosphere for any appreciable time.... Also, read the tech manuals and OBEY torque specs when changing these! Overtightening a gasket point is just as bad as undertightening it.
(6) Your universe of refrigerants is NOT limited to R-12 vs. 134. There ARE DOT approved drop-in R-12 exotic refrigerants. These so-called 'exotic' refrigerants are DIRT cheap when compared to the cost of R-12 today. A sweet approach is to hire one licensed to use/install an exotic to do a 'first fill' of the system, run the car for a month or two to VERIFY system integrity and then replace and fill with R-12. The drawback is, you can't go to Goodyear, Firestone, Etc. for this service since most auto A/C shops are ONLY licensed to handle R12/134....
(7) Whatever version of compressor you've got, MAKE SURE it's been rebuilt using the superior ceramic front bearing/seal kit Delco introduced for A-6 in the mid-70's. You'll NEVER regret the extra $5-10 you spend for this part vs. the early sintered version of the compressor's front seal that most all of the quick/dirty mass merchandise rebuilers use to cut costs and be competitive at the bottom line on the shelf at NAPA, Pep Boys, Etc....Comment
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R-12 direct replacement
the R-12 direct replacement is R-414B and is sold under the name HOT SHOT at places like jiffy lubeComment
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Agree
Agree with the "gut" approach to these older systems. I thought the lister was rebuilding the compressor, replacing every fitting, "O"-ring, hose, etc.. My point was that if he did indeed do that, and them vacuumed for a long time, he should be able to have some confidence in the integrity of the system.
Good point on the difference between vacuum and pressure. But I don't know how to get around that unless you fill, test for a while, and then evacuate. You'd need a licensed A/C shop do that job. That's why I'd convert to R-134a first and do it myself, but that's another story.Comment
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Re: Disagree....
Thanks guy for your input. FYI the system has had the compressor, stv valve, expansion valve and receiver drier all refurbished by Classic Auto Air in tampa and a new condenser. Classic auto has recommenended against anything but r12 or R134a.
They say the barbed fittings (all repros)and barrier hoses will leak a "little" with hose clamps. Nothing more than a top off at the beginning of the season. they prefer the crimped fittings. The local AC shop that will do the evac and recharge has said I will have big leaks with barrier hoses and barbed fittings. I am looking to hear from those who have this set up and what their experiences were.
My alternative may be to go with OEM freon hoses that will seal against the barb fitting and pay the price of r12.Comment
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Re: Disagree....
Jack - excellent advice. And that cermaic seal, well, they out to outlaw those cheapo sintered iron units!! I don't know how many times I had a rebuilt A6 that leaked, and, when I went in and replaced the seal with the GM ceramic seal.....fixed, end of story! The ONLY way to go IMHO....CraigComment
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Re: Disagree....
Classic Auto says they're going to leak a little. Local shop says they'll leak a lot. Both of them agree that the leak will be where the hose clamps onto the barbed fitting. Local shop's solution for that is crimped fittings. You want the barbed fitting because it's original. Have I got that right?
If you're gonna leak, leak R-134a. It's a lot cheaper, and you can top it off yourself. R-134a fill fittings are different than the original R-12 ones, though. You'll need to solve that problem. And buy a manifold with hoses to top off. ($75) You can buy the small cans of R-134a at your FLAPS for $5 each. Whole system takes about 3 cans to fill from empty.
I don't think the original hoses with the barbed fittings are going to seal any better than barrier hoses with barbed fittings. Wouldn't the problem be the barbed fittings? Not the hose. Just speculating. Don't know much about barbed hose fittings. Do know that crimped ones are better. What's the point deduction? Maybe it's worth it. I usually end up fixing things more than once. But I'd hate to set myself up for that. Maybe somebody here with more knowledge than I can tell you more about barbed fittings. Maybe there's a better way to seal the hose to them.
There's an Internet bulletin board on automotive air conditioning similar to this one. Go to www.aircondition.com.Comment
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Re: Disagree....
The barbed tubing that mates to the hos ID is there both on crimped and midyear hose clamp style exterior clamps. The barb bites into the inner hose surface, and the exterior clamp compresses the barbs into the hose lining. Regular refrigerant hose is soft enough to allow the barb to fully bite in and seal, preventing hose movement under pressure, as well as improving sealing. A barrier type lined hose will not imbed as well into the barbs on the fitting pipes, and will promote more leaks. A correctly assembled barbed design hose will not leak much, if at all..CraigComment
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Re: Disagree....
Craig and Chris,
Yeah you got it. I want to retain the clamps for originality. The barrier hose relies on the plastic liner to seal 134a (with higher pressures than R12) where OEM freon hose uses a more dense rubber hose and works fine on R12 only. if I were to go crimped fittings they change the barbed fitting to a smooth fitting to avoid cutting the barrier liner. The crimp locks in on a groove, this was referred to as a " beadlock" fitting aka crimped fitting. Since I want to stay with the clamps it looks like my only alternative is standard non barrier hose (if I can find some), clamps and barbed fittings. This is the original setup so I know that works. I was trying to give myself an alternative with 134A with the barrier hose but It looks like I can't have it both ways.
I was hoping to hear from C2 AC owners and what worked for them but it is a small universe. Thanks again for all your inputsComment
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Re: Disagree....
Randy - my 67 has the original barbed fittings and non barrier hoses, and I have had no leakage issues in 5 years since I purchased it. I think Dr Rebuild has the correct hoses, check him out....
Doc RebuildComment
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Dr Rebuild
Well, after I check, I see they are listed but NLA (No Longer Available) is in the price....guess the hoses are becoming a thing of the past...CraigComment
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Re: Disagree....
Craig is the GM ceramic seal still available from GM?Comment
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