Underbody AC lines for rear air

Do you have any idea what kind of pressures an A/C system operates at? You also have to use materials that won't be degraded by the refrigerant and oil in the system. Call around to the salvage yards and see if they have the line set off a wrecked AS.

Yes checked salvage they ALL seem to be horribly rusted. But maybe if I expand my search beyond the rust belt where I live. I am aware of the pressures, typically 300psi or less on the high side. I would not use tubing that was any less strong or of a different material than what the factory put in there. Aluminium or on my van steel. I was more interested to know if the barbs and clamps of old leak with R134a as opposed to the old R12 which they seemed to work fine with. But I can't imagine a springlock connector not leaking where a solid clamp would. Maybe I'm missing something. Thanks for the reply.

-- Mighty

This is where I get most of my used parts.

They have yards nationwide and can ship parts from one yard to another. I don't know if they inventory line sets, but they do have other A/C parts. The phone call is free, can't hurt to call and ask. I had a Crown Vic engine shipped from Memphis to SC, no extra charge.

If you had rust problems before, I wouldn't go back to stock steel. I'd probably opt for stainless, but then you're talking $$$. If you can only find an OEM replacement line set, there may be a way to coat them with something to protect them from rust, but not living in a rust belt area, I have no experience in doing that.

The leak problems are almost always caused by bad O-rings. They seem to be the weak spot, especially on Fords. Once you get a good set of O-rings in there, you generally don't have to worry about them again. Most of the problems I've seen are from shoddy 134a conversions where all the O-rings were not replaced.

Try 400 PSI plus for R-12. You could use hoses and clamps if the tubing has rolled lock-rings at the ends to work like fitting barbs, otherwise the hoses and clamps will blow right off the ends.

SAE Flare or double-flare can be done in the field, but you need to buy a quality flare tool. And the hard part would be adapting between Flare or O-ring fittings and the Springlock. If you can modify the other end and use new hose, Aeroquip has weld-on flare tips for many types of hard line.

If it wasn't for the vibration fatigue failure of hard copper lines, I'd go get a refrigeration lineset and run it on the same route. (In other words, don't try, it will fail early.)

You might have to go find the right size steel tubing that you can find fittings for, get a tube bending tool, and start duplicating. Swage the ends (or go one size smaller) and weld the tips of the old lines on the new, then paint and wrap the heck out of the new lines before you mount them.

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There's no MVAC usenet group, but there is a great internet forum:

This is a common problem on many vehicles with rear AC. One common solution is to get a line set for the same vehicle without rear AC. You lose the rear air, but if the cost of replacing the rear lines is prohibitive....

The copper lines may fail earlier than steel would, but that's years down the road. We had copper refrigerant lines on our waveguide cooling /drying system and oil lines on our primary generators when I was in the Air Force, and those lines were years old without any failures. I think you have the right idea about using flare fittings. It shouldn't be that big of a deal to braze on a male fitting to the steel lines that are still good and use female flares on the copper lines. Don't see any real reason why it wouldn't work.

SC Tom

If you had rust problems before, I wouldn't go back to stock steel. I'd probably opt for stainless, but then you're talking $$$.

If you know anyone that works at a local construction site, they can probably smuggle you out some stainless for free.

I could just buy tubing at home depot , clamp some barrier hose on and be good wouldn't one think?

Actually PVC line would work. I have a friend who replaced his lines with hard PVC tubing.

Too scary. I think it would soften from the hot compressed high side and burst.

-- Mighty

Yeah, I would have welded barbs to the ends of the tube.

Now this is a excellent idea!! I looked at the reuseable aeroquip fittings that are for their stanless braided lines and actually used them on my '92 Cherokee (still working great) but they only come in o-ring style fittings AFAIK. But flare fittiings are a great idea.

I thought briefly of using house style copper plumbing but did not know the pressure limits, didn't even think about fatigue. It pays to ask :0

-- Mighty

bob

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PVC pipe for refrigerant? Hell No! It's only rated for 125 PSI with water, and not at all for gases - the pipe tends to shatter when it bursts under gas pressure, people keep trying to use it for shop compressed air and it fails every time sooner or later.

And if you are in front of it when it shatters, you can be in a world of hurt or even dead...

Now you can use steel lines and slide PVC hose over them for cushioning and rust prevention, but if moisture gets between the steel line and the plastic hose you'll have the same problems.

A home refrigeration copper lineset would work and handle the pressures involved, and the insulation on the suction line would be a bonus for efficiency. (You would need some split corrugated loom tubing to pad and protect the liquid line.) Or you could get "HVAC Class" ultra heavy-wall copper pipe and bend it to fit - that's the stuff that comes in 20' sticks pre-cleaned on the inside and plugged.

But copper does work harden and crack eventually when flexed, and you would have to anchor it down every inch of the way (with padded clamps) to make sure it doesn't move.

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WOW. Neat idea! Their after picture does not show how they dealt with the springlock at the end.

-- Mighty

Are u sure about the price of having them made? Check around a bit. I think you are goin to have problems with clamps, u really need crimped on fittings.

Considerations.... the low side hose will rarely (if ever) see more than 100 PSI - The hottest it gets where I live is about 85ish F... I have no idea of what static pressures can hit in warmer climes.... With the AC operating, low side pressure will be more like 20 - 30 PSI

Conversely, high side pressures can reach as high as 400ish PSI depending on temperature and humidity.... (250 to 300 is the norm for a hot day for me). This is where home grown repairs will meet their match.... Trying to go too cheap on the repair might have you wasting the price difference on a self created hobby...

I added rear air to a Blazer years ago. Just bought some rubber AC hose of the appropriate size and ran it from the engine compartment to the rear evaporator and connected it with barbed fittings and clamps.

I tried to tell these clowns you could use rubber or PVC and they said it would explode from the pressure. The drugs they're taking must be causing a lot of water on the brain.

Excuse me, but you are wrong. Rubber High-Pressure Refrigerant Hose is not just "rubber or PVC hose" - it is specially made to handle the product at the normal operating pressures of 500 PSI. And the stuff is not cheap, even in bulk.

Gates Polar-Seal Hose - Comes in ID's of 5/16", 13/32", 1/2", 5/8".

have to register to bring up the Hydraulic Hose PDF catalogs.They have the fittings and O-Rings for the Ford Spring-Lockconnectors, and connectors with service ports built in. You could use standard steel or aluminum tube for the replacement lines, and the "flareless" hose fittings (Looks like "Swagelok" ring style) and a short chunk of Polar-Seal hose to transition at each end

- but that's making more places to leak.

You could build a specialty business selling conversion fittings so people could use standard steel brake tubing to make replacement rear air refrigerant lines, but there isn't that much volume of sales. If the solution costs too much they'll just clamp off the lines to the rear air and convert to front only.

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I've got an asshole like you that lives near me, thinks that everyone else's property is his, too. Good advice from you. . .NOT!