944 A/C Condenser Leak

[Tom]

Took the car yesterday on a 25 mile round trip and all seemed fine until I got home and noticed smoke/steam from under the car and a loud hiss up front. No dripping on the floor, nothing wet, tires not flat -- kind of a head scratcher. Disconnecting battery had no effect on the hiss. I have one of those Freon detection meters and it went crazy when I put it near the engine, but too crazy everywhere to find the source. So I made a low-tech detector that found it. See video.

This is a parallel flow condenser from Griffith's, which looks NLA on his website, so may to figure out how to replace or repair it. I'll take it out and get a better look at the leak first. I assume it took a rock or something, as it appears to be leaking in the cooling section and not at a seam or something. I did recently top it off (with gauges) but am thinking if I over filled it, it would have blown out a seal somewhere rather than this....?

[icb]

That's a bummer, Tom. I wish the Griffiths unit was still available, I'm gearing up to redo my air and it would have been a nice upgrade.

[Tom]

That's a bummer, Tom. I wish the Griffiths unit was still available, I'm gearing up to redo my air and it would have been a nice upgrade.

He replied first thing this morning and said he is out of stock with no ETA on when they might be back. So I'll see about fixing this one and, if that's a bust, will try the eBay one....

[Tom]

Well the radiator shop could not fix this condenser so I ordered the eBay one. Fingers crossed. There was a pin hole leak along a seam, which he fixed, but when he pressure tested it, the same seam kept splitting open further down the tube. Other than removing the whole tube and sealing the ends, it's kind of a bust. Suffice to say the radiator guy was pretty critical of the quality of the core.

[dr bob]

Drill a small hole at each end of the crack before welding, so the stress expansion from local arc heating is spread in more directions. Trying to TIG over a crack in aluminum tubing without opening the crack and terminating it with a hole is all but futile in my limited experience.

I've welded them with a rich acetylene flame too, plus there are some lower-temp "aluminum solder' products that work with MAPP gas. You still get to do all the same prep, but no purge gas and the lower melt temps mean way less chance of melt-through. TIG with a foot pedal and a high-frequency arc-start allows you to manage heat input is the best of course.

[Tom]

Drill a small hole at each end of the crack before welding, so the stress expansion from local arc heating is spread in more directions. Trying to TIG over a crack in aluminum tubing without opening the crack and terminating it with a hole is all but futile in my limited experience.

I've welded them with a rich acetylene flame too, plus there are some lower-temp "aluminum solder' products that work with MAPP gas. You still get to do all the same prep, but no purge gas and the lower melt temps mean way less chance of melt-through. TIG with a foot pedal and a high-frequency arc-start allows you to manage heat input is the best of course.

I'll pick it up in the next few days and do some forensics on it. Apparently it's not a crack in the metal, but rather a pinched seam running the length of the flat tube, which is not staying pinched under pressure. He tried to TIG it, but it would just keep opening up further down the seam under pressure. He tried to do the whole seam, but the metal itself then tore away under pressure -- or at least that's what I understood him to say. In any event, he's the last surviving pure radiator guy in town (40+ years doing nothing but), so I figure if he can't fix it, my chances are close to zero. I ordered the eBay one in the meantime. I'll probably strip the pipes and brackets off the old one so I can use them on a universal core if this ever happens again.

[Tom]

Happy to report I got my a/c system running again. I ended up installing the parallel flow condenser from Cooler Classics on eBay. Temps are as cold as ever it seems. There was only one minor fitment issue. For reasons I can't quite imagine, the mounting hole on one side was smaller than the other side, making it too small to slide over the rubber mounting nub on top. I took a Dremel to it so it matched the other side, and that fixed the issue. Only other thing I had to do was temporarily remove a screw holding the pipes to the side of the condenser (via a very flimsy bracket) in order to get the fittings attached. Maybe I was just being impatient, but I could not get the threads to line up with the screw in place, but once the hoses were all connected I was able to replace the screw. Overall, a pretty good, but not perfect, fit right out of the box. Although I'd say exactly the same about the Griffiths version. The Griffiths version 'seemed' higher quality, but mine failed pretty badly, so not really sure thicker brackets and pipes actually translate into a better condenser. Time will tell, but today I'm happy.

coller-classic-condenser.gif (547.32 KiB) Viewed 324 times

[dr bob]

FWIW --

In my extensive collection of 'lessons learned the hard way' is the reminder that heat exchangers like the condenser, radiator, oil coolers of various flavors and intercoolers must sit in floating mountings. They suffer and fail when they can't grow and shrink in normal service, and also when body/chassis flex tries to distort them. Old, hardened rubber bits are barely better than bolts. New rubber mounting bits are way cheaper than most replacement exchangers, it turned out for me. Might still be true.

[Tom]

FWIW --

In my extensive collection of 'lessons learned the hard way' is the reminder that heat exchangers like the condenser, radiator, oil coolers of various flavors and intercoolers must sit in floating mountings. They suffer and fail when they can't grow and shrink in normal service, and also when body/chassis flex tries to distort them. Old, hardened rubber bits are barely better than bolts. New rubber mounting bits are way cheaper than most replacement exchangers, it turned out for me. Might still be true.

Good info. I may still order new ones, but these are just a few years old iirc. I replaced them out of necessity with I installed the now-failed condenser just a few years ago -- or at least that's how I'm choosing to remember it. They did seem rubbery anyway....

Edit: ah, I see in the picture I say to transfer over from original condenser. What I should have said was 'these don't come with the condenser...."

[Tom]

Well, I said time will tell -- and time has now told. The eBay condenser leaks. Within a week, the refrigerant was too low for the a/c to kick on. My Harbor Freight sniff tester went crazy near one corner of the condenser, so that seemed to be the most likely leak (that, and the 'last thing you touched' theorem). I took it to a shop to evacuate the remaining r134a. While on the shop's machine, they pulled a heavy vacuum on the system and put it in test mode. His machine said the same as my HF gauges -- it passed with flying colors -- no loss of vacuum detected. I guess it needs higher pressures to leak (aka don't rule out leaks based on a vacuum test). My 30-day return window is closed, of course, but I may still see if the seller will exchange it, since it seems to be a production flaw. Otherwise, I may just by a new factory condenser and give up on the parallel flow.