Fixing a leak in the low pressure side A/C aluminum hard line (in a car) - Page 3

NiHaoMike · 08-07-14, 11:49 PM

Those air driven vacuum pumps are worthless for HVAC service. A converted refrigerator compressor would be superior.

Daox · 08-11-14, 10:06 AM

I started the work on the A/C system this weekend. Here are some pictures.

Here is the line still bolted down to the car.

Here is the p-clamp. It has yellow/green corrosion on it.

I cleaned up the line. You can see the pitting from all the corrosion. The hole is on the bottom, so you can't see it.

And here we have the JB weld repair job.

This afternoon I think I'll go pickup the vacuum pump from the autoparts store. I'll pull a vacuum and see if it holds. Again though, what oil should I put in this pump?

stevehull · 08-11-14, 10:20 AM

Humm,

My JB weld idea may not work so well at this location (a bend) in the AC line. If the line flexes, the JB weld may crack.

But it is worth a try . . .

Alternatively, how hard is it to get to the two ends? Remove the line, cut out the bad section and repair it (brazing).

The line "looks" like aluminum or steel.

Let's see how he vacuum test goes.

Steve

Daox · 08-11-14, 10:23 AM

In my googling of the issue, a few people said that their JB weld repair (on the low pressure side) worked just fine, one guy said his has been held for 20k miles. I figure its worth a try. The refrigerant isn't too expensive (~$15). So, if it does fail next year, we can replace the lines then.

Daox · 08-12-14, 09:36 AM

I pumped it down last night... and it seems there is still a leak... in both sides.

I also found out that hole was on the hot side, so I'm not sure the JB weld would even hold up to the abuse it would see.

Here is the pump I used. It is a 'rental' from autozone.

Here we have it all hooked up. I pumped it down for about 20 minutes. I didn't bother putting in new vacuum pump oil because this was just a leak test. I figured that is okay.

The pump ran probably 25 minutes. It doesn't look like it in the pic, but the needles on both gauges were pinned at their lowest setting for at least 15 minutes.

And, here we have a picture of the gauges roughly 15 minutes after closing the manifold valves and shutting off the pump. The cold side has a fairly substantial leak, and the hot side is also leaking.

Daox · 08-12-14, 02:46 PM

So, what do you say guys? Just grab a new set of lines?

jeff5may · 08-12-14, 06:02 PM

Quote:

Originally Posted by stevehull

Humm,

My JB weld idea may not work so well at this location (a bend) in the AC line. If the line flexes, the JB weld may crack.

But it is worth a try . . .

Alternatively, how hard is it to get to the two ends? Remove the line, cut out the bad section and repair it (brazing).

The line "looks" like aluminum or steel.

Let's see how he vacuum test goes.

Steve

99.9% likely that the hard lines are aluminum. Don't even try to braze the line. Aluminum is a lot like tin in the way it gets brittle with heat. It has a plastic region, like solder, so you can't spot weld it or braze it like copper. Just when the thing is about to fuse with your rod, the whole piece melts away like hot wax.

IF YOU WANT TO REPAIR THE HARD LINE, SAVE YOURSELF LOTS OF AGONY AND USE FLARE OR CRIMP FITTINGS!

Be sure to verify your leaks while the system is still together. If it is leaking inches of vacuum in a few minutes, it will be easy to find the leaks. Pressurize with nitrogen or other inert gas (argon, helium,etc.) to 100 or so psi. You can hear and feel big leaks, small ones require a spray bottle and soapy water.

AC_Hacker · 08-12-14, 11:02 PM

I'm coming in late to this conversation, but wouldn't it be a better idea to get a used line from a wrecking yard or else buy it new?

Why not make a copper one? It's just refrigeration. What's so magic about aluminum?

-AC

pinballlooking · 08-12-14, 11:10 PM

Yes I agree a junk yard like you pull it would work very well.
It would be cheap and work.

Do you have any of these close to you?

AC_Hacker · 08-12-14, 11:44 PM

By the way Daox, I just wanted to say what a beautiful vacuum pump you got youself there.

Rental you say? Sounds just great... you only need it for a short time.

Yes, and nice manifold gauge set too!

Just think, after you get your car air conditioner going... and you pick up just a few more minor tools, the doors of vapor-compression hacking wickedness will open wide before you.

You'll throw something together, make it work, and realize that you can build a machine with COP > 100%, out of pure junk.

Maybe even COP > 300%!!

Maybe more!!!

Oh boy, can't wait!

-AC

08-07-14, 11:49 PM	#21
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	Those air driven vacuum pumps are worthless for HVAC service. A converted refrigerator compressor would be superior. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

08-11-14, 10:06 AM	#22
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I started the work on the A/C system this weekend. Here are some pictures. Here is the line still bolted down to the car. Here is the p-clamp. It has yellow/green corrosion on it. I cleaned up the line. You can see the pitting from all the corrosion. The hole is on the bottom, so you can't see it. And here we have the JB weld repair job. This afternoon I think I'll go pickup the vacuum pump from the autoparts store. I'll pull a vacuum and see if it holds. Again though, what oil should I put in this pump? Attached Thumbnails __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-11-14, 10:20 AM	#23
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Humm, My JB weld idea may not work so well at this location (a bend) in the AC line. If the line flexes, the JB weld may crack. But it is worth a try . . . Alternatively, how hard is it to get to the two ends? Remove the line, cut out the bad section and repair it (brazing). The line "looks" like aluminum or steel. Let's see how he vacuum test goes. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

08-11-14, 10:23 AM	#24
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	In my googling of the issue, a few people said that their JB weld repair (on the low pressure side) worked just fine, one guy said his has been held for 20k miles. I figure its worth a try. The refrigerant isn't too expensive (~$15). So, if it does fail next year, we can replace the lines then. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-12-14, 09:36 AM	#25
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I pumped it down last night... and it seems there is still a leak... in both sides. I also found out that hole was on the hot side, so I'm not sure the JB weld would even hold up to the abuse it would see. Here is the pump I used. It is a 'rental' from autozone. Here we have it all hooked up. I pumped it down for about 20 minutes. I didn't bother putting in new vacuum pump oil because this was just a leak test. I figured that is okay. The pump ran probably 25 minutes. It doesn't look like it in the pic, but the needles on both gauges were pinned at their lowest setting for at least 15 minutes. And, here we have a picture of the gauges roughly 15 minutes after closing the manifold valves and shutting off the pump. The cold side has a fairly substantial leak, and the hot side is also leaking. Attached Thumbnails __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-12-14, 02:46 PM	#26
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	So, what do you say guys? Just grab a new set of lines? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

08-12-14, 11:02 PM	#28
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	I'm coming in late to this conversation, but wouldn't it be a better idea to get a used line from a wrecking yard or else buy it new? Why not make a copper one? It's just refrigeration. What's so magic about aluminum? -AC __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...

08-12-14, 11:10 PM	#29
pinballlooking Super Moderator Join Date: Jun 2013 Location: SC Posts: 2,923 Thanks: 172 Thanked 564 Times in 463 Posts	Yes I agree a junk yard like you pull it would work very well. It would be cheap and work. Do you have any of these close to you?

08-12-14, 11:44 PM	#30
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 723 Times in 534 Posts	Vapor-Compression Hacking Wickedness!!! By the way Daox, I just wanted to say what a beautiful vacuum pump you got youself there. Rental you say? Sounds just great... you only need it for a short time. Yes, and nice manifold gauge set too! Just think, after you get your car air conditioner going... and you pick up just a few more minor tools, the doors of vapor-compression hacking wickedness will open wide before you. You'll throw something together, make it work, and realize that you can build a machine with COP > 100%, out of pure junk. Maybe even COP > 300%!! Maybe more!!! Oh boy, can't wait! -AC __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker... Last edited by AC_Hacker; 08-12-14 at 11:48 PM..