I hope Cliff and the forum moderators won't rule this enquiry unacceptable.

I own a 1988 Fiero Formula; but this question about aircon relates to one of my other cars, and I know there are aircon experts among the PFF membership. The problem is also something which those who have done engine-swaps may have had to consider.

There are a couple of pinhole leaks in the high-pressure pipe (aka "liquid line") in the a/c system on my other car (which is, if you must know, a 2002 Lexus IS300).

I know where the leaks are because the R134a 'gas' refrigerant had fluorescent dye added, and this shows up in the light of my UV torch. The condenser is corroded and also leaks, but that is easily replaced. Right now the system is empty of gas, the a/c doesn't work, and there is no point in trying to recharge it.

The high-pressure pipe is a single piece of aluminium alloy tubing which runs from the condenser in front of the radiator, up to just behind the LH headlight where the filling-connection and the sight-glass are fitted on to the line. The line then goes down by the ECU and along the chassis-rail beside the engine block, and up to a connector in the firewall which links it to the interior of the car.

The bad news is that this line is a pre-formed tube with bends and turns,. It is therefore not flexible, so is tricky to disconnect and remove. And the OEM replacement part is discontinued and no longer available from dealers or any other supplier as far as I can establish.

So to get my a/c working again, I have to replace the condenser (not a problem) and that high pressure line.

As a new replacement line is not available, I have three options:

1) find someone breaking an IS300 and hope that the high-pressure line can be removed intact and undamaged. A bit of a gamble, as any such second-hand part will be about as old as my original and possibly equally prone to leaks. Nevertheless I am looking around breakers' yards...

2) have an aircon specialist make up a complete replacement part using mine as a pattern. This is possible, but expensive and hard to arrange as the only specialists I have found are a long way from where I live (in the Scottish Highlands). Removing the existing pipe complete is a challenge. Sending it by courier to an engineering firm elsewhere in the country is costly and risky as the pipe is hard to package, and fragile.

3) try to have the original pipe repaired. The original is 8mm or 5/16" outside diameter. Welding/brazing the pinholes is difficult and not certain to succeed. An option which I have discussed with a local hydraulic-hose workshop is whether the main length of the tube can be replaced; keeping the connections at either end, and using crimp-joints or compression-fittings to put a new section of pipe in in the middle. This raises two questions. What pressure does this pipe (the high pressure a/c line) have to withstand? And - linked to that - what could a replacement section be made of? Could it be made of brass... or copper... or some other alloy... or even suitably high-spec reinforced rubber or polyurethane etc hose? The advantage of this last option, if it is technically possible, is that a flexible section of hose would make reinstallation a lot easier.

These are obviously questions for an aircon expert. Any advice would be welcome!

Mastercool makes a product for aluminum repair that may be worth a try. I think it is available on Amazon and ebay if you can't find it locally.

https://mastercool.com/product/alum-bond/

Another option is to replacing the rigid tubing with modern flexible a/c “barrier” hose. It is relatively easy to work with and raw hose and fittings are readily available.

Thanks @Larryinkc for the suggestion about Mastercool Alum-bond. I had thought about using some epoxy-based product. But my concern is that it might be at best a temporary or short term repair. Applying the resin with the line in place is tricky (access is very tight and limited). But if replacing the line is difficult/expensive/impossible, this might be worth a try. Alum-bond is not cheap, though!

I like the idea from @Brian A of replacing the original rigid aluminium line with flexible 'barrier' hose. That would surely make reinstallation a lot easier. But I have various questions. Exactly what spec of hose is required? Apparently the a/c system runs a max pressure of around 350psi. I assume I'd need some kind of reinforced/braided hose. And exactly what material should the hose be made of? I seem to recall that R134a and other refrigerants tend to react with, or percolate through, certain types of rubber hose. Does the hose have to be PVC, nylon, or some other specialist material?

And finally, how would the connectors at each end (to the condenser at the front, and to the connection through the firewall) and the filling port and sightglass fitting, be connected on to the hose. Obviously I don't have crimping tools or kits: I guess i would need to seek the help of a specialist engineering workshop - who might need to know the relevant tech specs.

quote Originally posted by br1anstorm: Thanks @Larryinkc for the suggestion about Mastercool Alum-bond. I had thought about using some epoxy-based product. But my concern is that it might be at best a temporary or short term repair. Applying the resin with the line in place is tricky (access is very tight and limited). But if replacing the line is difficult/expensive/impossible, this might be worth a try. Alum-bond is not cheap, though! I like the idea from @Brian A of replacing the original rigid aluminium line with flexible 'barrier' hose. That would surely make reinstallation a lot easier. But I have various questions. Exactly what spec of hose is required? Apparently the a/c system runs a max pressure of around 350psi. I assume I'd need some kind of reinforced/braided hose. And exactly what material should the hose be made of? I seem to recall that R134a and other refrigerants tend to react with, or percolate through, certain types of rubber hose. Does the hose have to be PVC, nylon, or some other specialist material? And finally, how would the connectors at each end (to the condenser at the front, and to the connection through the firewall) and the filling port and sightglass fitting, be connected on to the hose. Obviously I don't have crimping tools or kits: I guess i would need to seek the help of a specialist engineering workshop - who might need to know the relevant tech specs.

A/C hose is a specialty hose. In the USA, a popular mail order is Coldhose.com.

Look around for a local hose shop. They are very common because there is high demand for repair/replacement of hydraulic and air hoses by trucks, construction and farm machinery. A/C connectors are (several) standard sizes. 350 psi is nothing: brake hoses must be capable of withstanding 3,000 psi.

I am no A/C technician but worked with a good one for years. Many A/C failures are because of "black death".

Read about it here.

You might know but one needs a vacuum pump and vacuum the entire system before charging with freon. And let the vacuum pressure of zero hold for some? time. Your issue seems likely to allow moisture into your system, which is a cause of black death.

I "think" the type of hose is important. Some are more prone to deterioration.

Thanks @cliffw. I have heard of 'black death'.

I have always sought to have the a/c systems on all my cars checked , vacuum-tested and serviced/recharged regularly.

I'm pretty confident that I don't have a systemic problem with the setup in my Lexus. The condenser and liquid line have developed leaks during the past year.

This is inevitable in cars over 20 years old, even if well-maintained, because metal weakens and corrodes.

The problem right now is that an OEM replacement line is not available. I am having to look at alternative options.

One might be to fabricate a new, different, flexible hose. This would need to be of suitable material to cope with the gas it carries without deterioration.

And it is precise advice on the type and specification of that hose - and how to fit the various connections to it - that I am now seeking.

Do please let me know if you can help with specific details on that.

[This message has been edited by br1anstorm (edited 06-07-2025).]

quote Originally posted by br1anstorm: One might be to fabricate a new, different, flexible hose. This would need to be of suitable material to cope with the gas it carries without deterioration. And it is precise advice on the type and specification of that hose - and how to fit the various connections to it - that I am now seeking. Do please let me know if you can help with specific details on that.

I will see if I can help but I have lost contact with my previous co-worker.