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Copper tubing?

MikeC5 on Sun August 30, 2009 7:53 PM User is offlineView users profile

Maybe a dumb question but are there any reasons (besides cost) that copper tubing could not be used for auto AC? It is widely used for home AC. Poor fatigue strength? It would sure be a whole lot easier to bend.. I don't suppose you can braze/sweat copper to aluminum...

GM Tech on Sun August 30, 2009 9:13 PM User is offline

Vibration would crack it -- yes poor fatigue strength.....

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......

chris142 on Sun August 30, 2009 10:44 PM User is offline

Originally posted by: GM Tech
Vibration would crack it -- yes poor fatigue strength.....

I don't know about that. My 47 year old Peterbilt has Copper air lines and they work fine. The thing will hold air for 3 days if not used which is longer than many new trucks will hold air.

Granted the air pressure is only about 110-125 psi vs 200+ for an AC system.

I think the secret must be to have the lines secured well so they don't move.

Karl Hofmann on Mon August 31, 2009 3:25 AM User is offlineView users profile

I have copper alloy brake pipes on my Jeep, so I can't see it being a vibration or pressure issue... Most likely it being car manufacturers being cheap. You can crimp aluminium to copper using Vulkan Lokring fittings... But they aint cheap

Never knock on deaths door... Ring the doorbell and run away, death really hates that!

NickD on Mon August 31, 2009 7:10 AM User is offline

67% copper/33% zinc heater cores, radiators, condensers were once very popular good corrosion resistance and can be cleaned with acid along with copper fuel lines. Like aluminum, different alloys were available in copper. Tend to go along that steel and aluminum is cheaper. but not only the material, the alloy, but the thickness of the wall. Suppose to buy a new vehicle, drive it for three years, then trade it in for a new one. If it burns too much fuel, government wants to get if off the road, want to smash it up, and entice you to buy a new one smaller thinner one. Making vehicles that are cheaper to melt down then to repair them. Food industry uses a much higher quality aluminum in throwaway pop cans than what the automotive industry uses, but they want you to throwaway your vehicle quicker than a used pop can.

GM started this concept in the 20's, Henry Ford was against it, still see many old Fords around, GM vehicles are rare, but that all changed in 1949, when they were all crap. Or is scrap a better word to use.

mk378 on Mon August 31, 2009 8:12 AM User is offline

Don't use soft solders such as tin/lead alloy or lead free plumbing solder. It's not recommended even on stationary refrigeration systems as it is prone to crack and leak.

iceman2555 on Mon August 31, 2009 9:00 AM User is offlineView users profile

Several import vehicles used brass/copper tubing for AC systems in the 80's. However, these were the stationary lines that mounted to the vehicle body. The compressor manifold mounted suction/discharge lines were rubber.
Answer to your question, is yes, they will work....but why. The modern AC system does not have the problem with hose leaks that were experienced in past years. The barrier hoses of today are far superior to those of R12 days. Yes, the systems still leak, but the majority of leaks now seem to be located at connections/orings or schrader valve areas.
If this is merely an exercise in how to waste time and money...then it is expected that that expenditure would be more beneficial in aiding the other poster that wants to install a house unit on his vehicle. Heck may even arrive at a patentable product !!!

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

NickD on Mon August 31, 2009 5:22 PM User is offline

Practical side of this story if using other than recommended replacement parts, is where do you buy the stuff? Certainly not at your local hardware of building supply store. Has to be purchased in mill quantity to precise specifications. Take the OP's question as one out of curiosity as to why don't they do this or that. Probably should just leave it that, but let's just say, vehicles are made to be recycled and the more the different materials used, the more difficult it is to recycle. EPA is really pushing this.

MikeC5 on Mon August 31, 2009 9:15 PM User is offlineView users profile

The main reason I asked about copper is the relative ease of bending it into the oddball line shapes. As you say Iceman, one would still want the flexible hose connections to allow movement, isolate vibration etc. I know the conventional auto AC tubing materials are steel and aluminum. From what I've read, steel is relatively easy to braze, aluminum isn't. But steel would need to be plated or at least pained before installation or it will rust. I'm not an expert at any of these things but I'm not afraid to spend a little money learning. If I had bags of money I'd simply have someone make the hose assemblies for me or better yet, have someone else fix the AC...

ghiotom on Mon August 31, 2009 9:16 PM User is offline

I think the aluminum tubing they use in auto AC's bends about as easily as copper. Weld/braze/solder is more difficult with aluminum, but with a little practice, is not hard. And aluminum tubing and splices are fairly cheap and readily available.

NickD on Tue September 01, 2009 6:02 AM User is offline

If you are talking about soft copper tubing found in hardware stores, yes, it's easy to bend, but if you are talking about semi-hard copper tubing used in AC systems, not easy to bend, if done cold, can even break. Ever try to bend a rigid copper pipe? Then, are you talking about the 3/8" high pressure line or the 3/4" suction line? In HVAC applications, using rigid with elbows lately to make those curves.

MikeC5 on Tue September 01, 2009 10:16 AM User is offlineView users profile

The only stuff I'm familiar with is the soft bendable copper. I'm condsidering re-making all of the lines so 3/8, 1/2 and 5/8 are what I'd be using. I would guess the copper alloy is still easier to braze than aluminum. Do you have any idea what spec to ask for to get the rigid copper tubing?

Probedude on Wed September 02, 2009 12:57 AM User is offline

The aftermarket dealer installed a/c system in my Metro has a copper tube/aluminum fin condenser and the lines to the drier are copper too. Living on the coast with the salt air, the copper is corroding from the outside in. Still intact but it looks ugly.

I can't get replacement radiators to last more than 2.5 years as they're copper tube/finned also and the fins all rot out from the salt air.

ScotY on Tue September 15, 2009 3:54 AM User is offlineView users profile

I saw an aluminum brazing video on another website that made it look REALLY easy. I always thought soldering/brazing aluminum was very difficult. They sell these pre-formed rings of flux core solder, you just put it at the joint, heat the whole thing up, and it flows right in there. I'm still a little skeptical though.

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