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Pretty sure evap tubes shouldn't look like that

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knobbler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote knobbler Quote  Post ReplyReply Direct Link To This Post Topic: Pretty sure evap tubes shouldn't look like that
    Posted: Aug/02/2018 at 8:58pm
Putting my HVAC back together currently. Got the heater core box done(ish), moved on to the evap.

Looking it over, it's definitely showing its age. I'm concerned about one of the fittings, but more troubling to me are these:




These pockmarks look like they've pushed out from under the metal of the fins. My first thought was that they were indication of a refrigerant leak making its way out. Then I thought it might be signs of moisture finding its way between the tubing and the fin material. At that point, I realized that I just don't know enough about the construction of the evap core to say what it is with any certainty. Heck, for all I know, these are normal.

That said, I think there's some level of indication that there was a leak nearby. I just got done using a die grinder to remove one of the fittings.



This was so corroded that one of the walls was about halfway rusted away. The top two threads of the brass fitting it mated to were actually visible through the hole that had rotted out. The rest of the fitting was mostly fine, except the collar as shown in the pic.

The other fitting still has all it's walls, but is rusted at the collar. Since it won't budge at all without risking twisting or bending the evap tube, it seems some attention from the grinder is going to be needed free it. That seems like a problem to me, since it's a fitting on the evap and not a hose. Here's a picture of that one.



Since the extreme corrosion on the first fitting seemed to be strangely localized, I'm wondering if it wasn't an effect of a reaction between the metal and refrigerant leaking and being exposed to moisture. The system was said to still be R12 when I bought the car, but the compressor had R134a fittings and seals. Since the corrosion looked to have been well underway before I got the car, my suspicion is that the R12 was leaking out, producing acid from being exposed to condensation, and caused the fittings to corrode. The pockmarks are evidence of condensation making its way under the fin material, then escaping through it after vaporizing. In short, the evap is no good, or has little life left in it.

Does any of this make sense, our am I completely bonkers here? Both?

My buddy should be getting an AC manifold tomorrow, so I could try to wrestle with getting the expansion valve off and drawing a vacuum. Honestly, I have a loooooot more work to do elsewhere, and would rather spare myself the time spent doing all that if I can.

Any input from y'all will be most welcome. Thanks!
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White70JavelinSST View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Aug/03/2018 at 10:47am
Knobbler,

Did you see the pictures included in the AC in 70 Javelin thread?

I made a male o-ring fitting out of copper tubing and got my buddy to machine a female o-ring fitting from a brass mip to flare fitting and silver soldered them onto the tube ends of the evap coil. It worked great
70 Javelin SST, second owner, purchased 1972
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knobbler View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote knobbler Quote  Post ReplyReply Direct Link To This Post Posted: Aug/03/2018 at 9:49pm
I had not, actually; thanks! That sounds like a really good suggestion. I'll go take a look at the other thread now.
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