TurboDennis
SILVER Star
So found myself in a pretty desperate situation.
TLDR: Can i join an aluminum AC line with an inverted double flare union?
I have installed the console fridge into my truck and replaced the associated A/C lines with the correct ones that i sourced from middle east.
System didnt hold vacuum for long, and i found a couple of small pinhole leaks on one of the high pressure hardlines that run along the firewall from drivers side to the passenger side.
So i removed the lines (a banana job) and tried to repair the leaks. I used the aluminum brazing rods on the holes, and then smothered the area with special epoxy designed for aluminum A/C lines (on top of brazing) for good measure.
Pressure tested the lines on the bench to 400 psi. They held. Installed. Held vacuum for an hour. So i charged the system. A week later the A/C starts blowing hot air. The repair failed..
Im determined to have the A/C working, so i sourced proper 8MM aluminum tubing (VERY difficult in Canada) and decided to make a brand new lines and attach original fittings to them. I cut the fittings off with a couple of inches of tube sticking out. Made new lines. Swaged the ends so that the stubs with the fittings would fit inside tightly. Tried to braze/epoxy these joints again. Leaked at 100-150psi on the bench.
So I made new lines again and went looking for a good TIG welder to weld the fittings on. Called/visited about 2 dozen welders and fabricators. Everyone either didn't want to take on the job because it was too small, or think they were capable of welding it properly. Only one guy has agreed to do it. He welded up the connections (old fittings with a stub to newly made line). Pressure tested on the bench. Tiny leaks at ~150psi.. The welds also melted through and reduced the I.D. of the lines significantly.
So at this point I've wasted about 50 hours of my time on this line and a few hundreds of dollars and im not any closer to having working A/C.
-New lines are no longer available from Toyota.
-Sourcing used lines is extremely difficult from middle east and i dont want to risk getting a leaky line again.
-Replacing the hard line with a flexible rubber line is not an option due to lack of space where this line runs.
- Using a specially designed A/C compression fittings to join the old line to new is also not an option for the same reason.
- TIG welding, while possible, has proven to be unreliable.
So this brings me to to my question. Is there anything wrong with putting an inverted double flare on the ends, and using a union (with 2 flare nuts) to join the lines? The union is much skinnier than the compression fitting so it shouldn't cause any interference issues. I checked and the aluminum line flares easily and flare looks great. This type of joint works great on brake lines that see up to 2000psi, so i dont see why it wouldnt hold on A/C line that will only see 200-250psi. I have done some research online and i cant find any evidence of people doing this type of repair on automotive A/C's. Is there a reason why?
Joint and the failed TIG weld:
Double flare on a test piece
TLDR: Can i join an aluminum AC line with an inverted double flare union?
I have installed the console fridge into my truck and replaced the associated A/C lines with the correct ones that i sourced from middle east.
System didnt hold vacuum for long, and i found a couple of small pinhole leaks on one of the high pressure hardlines that run along the firewall from drivers side to the passenger side.
So i removed the lines (a banana job) and tried to repair the leaks. I used the aluminum brazing rods on the holes, and then smothered the area with special epoxy designed for aluminum A/C lines (on top of brazing) for good measure.
Pressure tested the lines on the bench to 400 psi. They held. Installed. Held vacuum for an hour. So i charged the system. A week later the A/C starts blowing hot air. The repair failed..
Im determined to have the A/C working, so i sourced proper 8MM aluminum tubing (VERY difficult in Canada) and decided to make a brand new lines and attach original fittings to them. I cut the fittings off with a couple of inches of tube sticking out. Made new lines. Swaged the ends so that the stubs with the fittings would fit inside tightly. Tried to braze/epoxy these joints again. Leaked at 100-150psi on the bench.
So I made new lines again and went looking for a good TIG welder to weld the fittings on. Called/visited about 2 dozen welders and fabricators. Everyone either didn't want to take on the job because it was too small, or think they were capable of welding it properly. Only one guy has agreed to do it. He welded up the connections (old fittings with a stub to newly made line). Pressure tested on the bench. Tiny leaks at ~150psi.. The welds also melted through and reduced the I.D. of the lines significantly.
So at this point I've wasted about 50 hours of my time on this line and a few hundreds of dollars and im not any closer to having working A/C.
-New lines are no longer available from Toyota.
-Sourcing used lines is extremely difficult from middle east and i dont want to risk getting a leaky line again.
-Replacing the hard line with a flexible rubber line is not an option due to lack of space where this line runs.
- Using a specially designed A/C compression fittings to join the old line to new is also not an option for the same reason.
- TIG welding, while possible, has proven to be unreliable.
So this brings me to to my question. Is there anything wrong with putting an inverted double flare on the ends, and using a union (with 2 flare nuts) to join the lines? The union is much skinnier than the compression fitting so it shouldn't cause any interference issues. I checked and the aluminum line flares easily and flare looks great. This type of joint works great on brake lines that see up to 2000psi, so i dont see why it wouldnt hold on A/C line that will only see 200-250psi. I have done some research online and i cant find any evidence of people doing this type of repair on automotive A/C's. Is there a reason why?
Joint and the failed TIG weld:
Double flare on a test piece
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