LG LMXC23746S Fridge not cooling

[6010fd12]

On 6/15/2020 at 8:16 PM, ECtoFix said:

Brazing with MAPP is a challenge since they changed the formula several years ago.  Too much torch time on the lines can damage other components.

Looks like you did good. 

Thank you.

 

Ok. Here's an update. I did the pressure test. Low side stayed right at 155 psig and didn't move at all but the high side went from 145 psi to 100 psi in the span of 24 hours. I switched the low and high side hoses just to be sure and within 2 hours high side went from 149 to 140. After a couple of hours I finally found the leak. It's right by where the yoder loop connects to the drier from steel to copper.

 

At this point unless you think this is doable with a MAPP torch(reflow the braze?), I think I am ready to call a professional to braze this. I don't want to fuck with steel to copper, especially in such a tight corner with a torch that has a 1" diameter flame.

[Vance R]

If you don't care about looks you can cut open the sheet metal and carefully bend out some tubing to make the repair. Then repack the old insulation and fold down the metal then cover with foil duct tape.  To practice you can get some steel brake line tubing at the auto parts store. 

BTW i've never ever broken the tubing off at the cabinet and had to do this style repair 😎.

 

[6010fd12]

8 minutes ago, Vance R said:

If you don't care about looks you can cut open the sheet metal and carefully bend out some tubing to make the repair. Then repack the old insulation and fold down the metal then cover with foil duct tape.  To practice you can get some steel brake line tubing at the auto parts store. 

BTW i've never ever broken the tubing off at the cabinet and had to do this style repair 😎.

 

Would this work for practice? I couldn't find anything cheaper. Also so if I pull out some of the tubing from the cabin, would I be able to just heat up the braze to let it reflow into the joint or do I just need to cut off that steel to copper connection and redo it from scratch?

[Vance R]

Just go to autozone or napa and get a 3' section. https://www.napaonline.com/en/p/BK_8131206?partTypeName=Brake+Line&keywordInput=brake+line

 

You could try cleaning and fluxing to reflow. If you get good at practice pieces just cut it off and start fresh.

[6010fd12]

3 minutes ago, Vance R said:

Just go to autozone or napa and get a 3' section. https://www.napaonline.com/en/p/BK_8131206?partTypeName=Brake+Line&keywordInput=brake+line

 

You could try cleaning and fluxing to reflow. If you get good at practice pieces just cut it off and start fresh.

Gotcha. Going to try that. Thank you.

[6010fd12]

I forgot to ask. I know you said you have never done this type of a repair before but where do you think would be the best/safest place to start cutting/bending and the best tool to use (dremel/sheet metal cutters)?

[Vance R]

Oddly it would be a screwdriver or thick putty knife. Tap tool in at 45 deg angle on it's corner into the sheet metal about 1/16".  Then tap  tool with a small hammer to cut the metal. Cuts easy for the most part. Wear gloves to fold the metal back and use tool to dig out insulation. Try to get big pieces as the insulation bits will get everywhere in the work area.

[Budget Appliance Repair]

On 6/16/2020 at 8:35 PM, Vance R said:

BTW i've never ever broken the tubing off at the cabinet and had to do this style repair 😎.

@6010fd12 I'm pretty sure @Vance R has actually done this repair before - that was just kind of a tongue-check remark, (see smiley at end)?

[6010fd12]

@Budget Appliance Repair I honestly don't know how I didn't catch that. Lol. I don't do hvac for a living so I don't know what's "norm" and what isn't.

Also do I need to go farther than this? I'm able to bend it down maybe a 1/4" but I'm not able to pull it out of the insulation. I just don't want to go too far and mess something up.

[Vance R]

@Budget Appliance Repair unfortunately done this many times to save a refrigerator, still kinda feels like a shade tree repair. 

@6010fd12 you can cut the bottom part straight back to the tubing hole so you can bend tubing out alittle more for extra clearance. Some of this boils down to your comfort zone with your torch. 

[Budget Appliance Repair]

11 hours ago, Vance R said:

done this many times to save a refrigerator, still kinda feels like a shade tree repair. 

Sometimes you just got to do what you got to do to save a $2000 box - fortunately for me, I don't get involved with sealed system work so don't have these issues!!!!

[6010fd12]

Ok so I managed to pull some tube through the bottom but I have caved in and decided to purchase a port-a-torch kit from home depot. What size tip would be the best for me? I am looking for a small flame that would help me be able to reach into tight spaces.

[Vance R]

Couldn't get link to work.  I use victor j100 series with a #1 tip.

[6010fd12]

Now sure why they don't work. Here is the link.

https://www.homedepot.com/p/Lincoln-Electric-Port-A-Torch-Kit-with-Oxygen-and-Acetylene-Tanks-and-3-16-in-x-12-ft-Hose-for-Cutting-Welding-and-Brazing-KH990/206959650

 

Do you think that tip will work with this unit?

[Vance R]

The link takes me to a rig with a cutting torch head. Just a normal welding tip should be fine 0 or 1 should be good.

[6010fd12]

I went with the same unit you reccomend to me because the Lincoln electric didn't come with a DOT acetylene cylinder. When using the 0 tip what psi should me regulators be at?

[Vance R]

You can review the instruction manual for the manufacturer recommendations. I prefer 7psi and 7psi, but must mention my set is older and gauge are not accurate.  The hardest part about using oxy- act torches is learning how to get a proper flame. You have to balance the oxygen and acetylene for a neutral flame. Also you can make the blue cone very large to very small depending on adjustments. Large the blue cone the more heat it will put out and the tail will be longer. Watch a couple of youtubes if you need to see what the neutral flame cone should look like with it is correct. Next personal preference for me is to make the flame slightly rich with act, the blue cone will have just a slight extra feather.  One more thing after learning how to get a correct flame this is to prevent having a sooty flame at start up. crack the oxy valve first and then open act valve then light the flame. Then when shutting off you have to break normal welding rules and turn off act first to blow the flame out. The soot is black and oily, floats in the air and very hard to clean up - this is really important when in a home doing this work. Since you probably in a garage these detail are not important at first.

[6010fd12]

I was able to repair the leak. Pressure tested it to 160 psig over 48 hour and not a single drop in pressure over that time. I finally went to vacuum it out and after reaching below 1000 microns I turned the ball valves to isolate the whole system and my micron Guage kept creeping 20 microns up every couple of seconds indefinitely. I spent a good day pulling my hair out thinking there was another leak until my adaptor came for the supco VG46 and I was able to test it for leaks by itself. Turns out it was leaking air internally. Thank god Amazon let me return it after the 30 days. I should have listened to the reviews.

 

Could you recommend me a good micron guage that won't leak?

[Vance R]

Mine is the uniweld copy of bluvac. Have a coworker that has the testo inline one. 

[6010fd12]

I ended up going with a Testo 552 from Amazon. I want to be able to clean out all my hoses, fittings, and manifold Guage before it arrives. 

Would I be able to do that with 91% isopropyl alcohol and nitrogen?

[Vance R]

The main counter guy at RSD in my area uses NU-Calgon Degreasing Solvent LV in aerosol can to clean hoses for rebuilding low loss fittings. Seem to work good on hoses to remove oil residue.

[6010fd12]

So my new gauge came and I tried to test if it would hold a vacuum by being directly connected to vac through a female to female adaptor and a ball valve but even after getting down to 50 microns or so as soon as I close the ball valve the number jumps to 1000 and climbs up very slowly. I'm not sure if this is supposed to happen or not or if I need to keep it down at the low of a reading more than 3 minutes and then close it off to keep that vacuum.

 

Either way I decided to try and see if I can evac the system to 500 microns and keep it below 1000 once it's shut off. It took 1 hour and 28 minutes to get down to 462 microns and within 28 minutes after I closed the valve it rose up to 830. That was last night and when i checked this morning it is at 5055.

https://docs.google.com/spreadsheets/d/1kMyFxrMieHbw41J8QTgh2GI6-W_xckZDY3VUEbm5Koc/edit?usp=sharing

So I am guessing I have a small leak but the big question is if it's in the gauge or fittings themselves or the fridge. 

[6010fd12]

Forgot to include this. Here is the setup I have and I have a feeling that since the vaccum didn't hold on my first test with just the micron guage, it has to either be the female to female fitting or the micron guage.

[Vance R]

Believe the testo micron gauge goes inline, no need for a tee.  Lets see, ball valve on lowside valve to adapter then on to the testo, then your blue hose. You may just suffering from connection leaks from your equipment.  I would just remove the testo and hook manifold gauges to the refrig. Use ball valves on all 3 hoses. Hook yellow hose direct to vacuum pump and pull vacuum for 15 to 45 minutes. Shut off the yellow hose ball valve then turn off vac pump. Next step will depend if your using a scale to weight in charge. Think you are using small automotive cans - you'll have to setup can on scale with your adapters for vapor. I place the vacuum pump on the yellow hose about in the middle so moving the gauge doesn't effect the reading on the scale. Turn off both hand valves on the manifold and then open ball valve on yellow hose, turn on valve at the can or tank. zero the scale after scale reading stabilizes. Once you have a good steady zero open the highside hand valve,  watch the lowside gauge to see if vacuum break and start rising to zero. When lowside gauge gets near zero you can open lowside hand valve. This procedure is to check for blocked cap tube.  if the scale should stop climbing before target wait is reached close highside hand valve and plug in refrig. when the compressor starts it will suck in the refrigerant. turn off lowside valve at correct weight.  Then turn off tank valve, let it run for awhile (few minutes) to an idea of pressures. depending on air temp you should see lowside drop down to 15 to 25 psi and highside be 95 to 110ish.  Next is to bleed the hoses - turn off ball valves on yellow and red (highside) hoses - open the highside hand valve, this will let the refrigerant in your hose be pulled into the system. Once pressure stops dropping turn off lowside ball valve and remove gauges. 

[6010fd12]

Gotcha I am going to try that out right now. One question though. If the testo goes inline and a good vacuum is pulled; when it's time to add refrigerant is it safe to let it pass through the testo? On any video that I watch with a vac guage they always have it attached to the service port of the valve core removal tool and isolate it with a ball valve when it's time to add the refrigerant.