What is best pipe for automobile AC?

Question

What is the best pipe for automobile AC

Coper Aluminum Flexible hose

I'm planning to install new AC for my Landrover, appreciate your advice

Thank you

Answer 1

My first job in the automotive industry was as a 'hoser', designing heater and air conditioning (A/C) hoses for a US based automotive manufacturer as an automotive engineer.

A/C hoses are made of steel tubing (coated or painted for anti-corrosion protection) or aluminum (sorry, I don't remember what grade aluminum) with rubber/ thermoplastic hose when necessary to accommodate engine movement or odd installation requirements.

Steel is the easiest to use, but not the absolute best for corrosion or weight. The flexible hose material is a big deal. It's a series of polymer / rubber extrusions designed to be 'flexible' yet contain the molecules of refrigerant. And yes, don't cut corners here. Different refrigerant molecules require different hose specifications (Freon vs R134 are dramatically different.)

You are going to need a nice hydraulic crimper to join the flexible hose to the end of your steel tube. Two or three thousand dollars should do you... including crimp dies. Note there are formed barbs on the ends of the metal hose to improve joint retention. Don't crimp these up smooth. Certain to fail (ask me how I know!)

Tips and hints.

• To make stuff pretty its best to route the hoses along X, Y lines within the engine compartment. Go left, right, car forward or aft... angled stuff just looks way odd.
• Because of engine roll during vehicle operations, you will have to place flexible hose section between the A/C compressor and the rest of the engine compartment, to accommodate engine movement, but that's just a piece of it.
• Flexible A/C hoses are still pretty stiff. You MUST add some bend in the flexible hose to reduce stress. This is a difficult concept to describe, so bear with me... you will want at least 90 degrees of bend in the hose, if not 180 degrees or more.
• Heres a 90 degree bend..

• And here's a zero degree bend. Do NOT do this. It's not clever. It may work for a while (as the axis of rotation of engine roll happens to be parallel to the hose) but if that car every got transported on a trailer, where engine movement will be random, that A/C condenser will be broken in no time..

• You want the flexible part of the hose to be as long as possible with minimum 90 and preferred 180 degrees of bend to reduce stress on parts everywhere.
• When you are trying to figure out hose routing in crowded engine compartment get yourself a three foot long piece of heavy gauge copper wire. Use this to simulate what you are proposing. Analyse what happens during engine roll. Get the shape exactly correct before you bend up a steel or aluminum tube.

I will say, this stuff isn't totally cheap or easy to do. I suspect you'd be saving a whole lot of time and money by just purchasing factory made parts. What's driving you here? Is that stuff not available? Perhaps in a salvage yard somewhere?

Good luck with your project...