LG LMXC23746S Fridge not cooling

[Vance R]

The Harris rod you picked are just prefluxed, you can use 45% rod and flux paste. The sil fos can be any brand. I use it because johnstone and RDS in my area carries it. Any refrigeration supply place should have correct tubing. Anyone in your area do sealed system work - they may have some small quantities. 

19 hours ago, 6010fd12 said:

Do I need to worry about the oil inside the system at all?

Yes, keep the system sealed as much as possible the oil is hydroscopic (it attraches moisture).

 

19 hours ago, 6010fd12 said:

And also do I need to install a new UV Dryer or can I keep the current one on?

You will need to replace dryer, it does have to be a uv dryer. Plain one will do ok.

[6010fd12]

1 hour ago, Vance R said:

Yes, keep the system sealed as much as possible the oil is hydroscopic (it attraches moisture).

I don't need to replace any of the oil correct? I'm just worried that purging / vacuuming / recovery will remove oil from the system.

 

1 hour ago, Vance R said:

You will need to replace dryer, it does have to be a uv dryer. Plain one will do ok.

Would this one work? I heard that it's a very cost effective dryer.

[6010fd12]

Or this one.

[Vance R]

Shouldn't have to change oil. Just keep the system sealed as possible

Either drier will work fine.

[6010fd12]

22 hours ago, Vance R said:

Shouldn't have to change oil. Just keep the system sealed as possible

Either drier will work fine.

I'm not sure there is a leak in the system or if anything it must be a very small one. Pressure tested the low side at around 50 psi and after about an hour and a half it stayed at or close to the initial reading. I also sprayed all the lokrings fittings with NU-CALGON Leak Detector and no bubbles. I decided to test the high side over night. I set it to 145 psi and I moved the hose a little and it settled down at around 143 psi. If it reads close to that reading in the morning I'm going to test the low side again at around 150 psi for a couple of hours to see if it changes.

[Vance R]

Check the model number tag for design pressures. 400 psi for high and 140 psi for low are common.

[6010fd12]

13 minutes ago, Vance R said:

Check the model number tag for design pressures. 400 psi for high and 140 psi for low are common.

I don't have the tag sadly. The owner told me that after the tech was done they removed that label and gave him a partial refund. Do you know where I can lookup that label online for my specific model?

[Vance R]

21 minutes ago, 6010fd12 said:

Do you know where I can lookup that label online for my specific model?

Not sure where to look.  Your 140/150 psi should be safe. 

[6010fd12]

16 hours ago, Vance R said:

Not sure where to look.  Your 140/150 psi should be safe. 

Ok so I came back 17 hours later and the high side has dropped down a significant amount. Before I pressurised the high side I made sure that there was nothing in the low side and hooking up the low side today it seems like the pressure that is missing in the high side has made it to the low side. Is this normal?

[6010fd12]

I checked out the freezer evap and its squeaky clean. The only thing I found on the fridge evap was this. Besides the lokring fittings which I have leak tested I don't see anything else that I can check. Do you think I should go ahead with the vacuum test?

 

Edit: Just as I was typing this I decided pressurise both side to 150 and I HEAR IT! It hear a very faint hissing coming from the fridge evap somewhere around the location where I posted those two pictures

[6010fd12]

I found it it was in the fridge evap coil.

[Vance R]

3 hours ago, 6010fd12 said:

I found it it was in the fridge evap coil.

Looks like you found the leak everyone else missed.. 

To test the highside you isolate the tubing coming out of the compressor discharge for one end and the other end is the tubing going into the drier. You are testing the condenser and yoder loop ( hot gas pass) for leaks. Nothing else can be attached.

[6010fd12]

On 5/29/2020 at 7:59 PM, Vance R said:

Looks like you found the leak everyone else missed.. 

To test the highside you isolate the tubing coming out of the compressor discharge for one end and the other end is the tubing going into the drier. You are testing the condenser and yoder loop ( hot gas pass) for leaks. Nothing else can be attached.

Is there any way to purge and pressure test one of these evaps off ebay before connecting it to the system?

[Vance R]

It would require the robinair process adapter kit. Next would be if the original rubber plugs in the new evap have not been disturbed, the evap come precharged with nitrogen. When you pull a plug there should be a slight discharge. Same goes for new compressors.

[6010fd12]

Sorry for the long delay. After practicing my brazing on some scrap 1/4" tubing I am going to be attempting to replace the evap this weekend. The evap that I received looks like it came straight from the factory (came in an LG Service parts box and all tubes plugged) so I don't think I need to worry about that. Can you run me through step by step on how I can detach and reattach the new evap?

 

I know I need to have all valve cores out the high side and low side while I flow nitrogen through and I will be protecting all the components with heat blankets and heat putty. My only concern is how I'm going to get the evap off. I don't want to cut any of the lines and risk having my tubing be too short to install the new evap but I have a bad habit of pulling a little too hard on my practice pipe with my pliers while brazing to try and the pipe gets squished while I try to take it out. Is there any technique to this? Also how do I remove to capillary tube from the evap and make sure that the end isn't clogged?

 

Here is a picture for reference. 

[Vance R]

8 minutes ago, 6010fd12 said:

My only concern is how I'm going to get the evap off. I don't want to cut any of the lines and risk having my tubing be too short to install the new evap

We'll start here, to unsolder or unsweat a tubing joint you break the rules of good silver soldering. Light pressure, pull straight - no wiggling and heat the outer tubing more than the inner. If you can get old compressors they are great to practice on, tubing usually over laps about 1". If that not possible unsolder your practice joints. This will work for the suction line (larger tubing).  BTW you have enough tubing to cut right next to the braze joint with a IMP tubing cutter. Personal choice. You can make your life easier by using side cutter to cut the aluminum tubing next to the copper transition to remove the main part of the evap. Then remove the stubs.

Now on to the capillary tube, LG crimps the cap tubing somewhere between the liner and braze joint to reduce refrigerant noise.  I recommend scoring the cap tube right next to the crimp on the liner side. Don't worry about it being too short you'll take a box knife and cut the liner from where the suction line and cap tube exits the wall about 3"to 4". Don't go too deep with the knife, just cut the liner. You can pull out some of the cap tube. They tell me you pull about 4" out, i usually just do a couple inches. Remove the crimp reduces the chance of getting a restriction in the cap tube.

After the evap and/ or the stubs are removed sand the suction tubing end with sanding cloth. For the cap tube sand and area about 1" from the end. Leave the end "dirty", some guys use face oil to contaminate the end of the cap tube to prevent soldering it closed. Sand the ends of the evap tubes, you can use small round wire brush to clean inside of the suction side.  Preassemble the evap to fit everything in place. I prefer to "over bend" the suction line so that it wants to push together to prevent it from pulling apart when heated.  Some prefer to put a light crimp to hold the tubing together. Insert the cap tube about and 1" and put a slight bend in the cap tube so you know how much it moves when heated. You can "over bend " or crimp.  Heat paste or wet towel to protect tubing coming out of the liner and at the copper to aluminum transition.  Use blaze barrier where you think you need to protect. Remember the trail of your flame, it will melt/burn things. You can use 15% silphos for both joints.  

[Vance R]

Seem something familiar today

[6010fd12]

I first off want to say WOW I thank you for going into such depth. I went to inspect the cap tube today and I seen the crimp you were talking about. I wanted to try and pull the cap tubing out like you mentioned before I removed the evap so I cut the insulating foam up to the plastic wall and I went in with a small serrated kitchen knife and cut around the tubing all the way to the the back being very careful not to scratch any of the pipes. At first I tried pulling the cap tube straight backwards being careful but all it did was make a small crack in the plastic housing then I tried pulling straight up as hard as I can without damaging the tube and it did not budge a single bit. I had someone watch where the cap tube exits in the back to see if it moved at all but it didn't. Am I being blocked by some insulation or do I need to cut out some of the plastic housing? I am only using my hands to pull and not pliers as to not crimp the tube by accident. 

[Vance R]

So it was a two evap day, here the other where i cut the liner and pulled out cap tube

[6010fd12]

OHHH ok so you do cut the plastic backing! Gotcha. That makes sense. I though I was supposed to pull it up from the hole. What face oil do you recommend I use? I have this on hand but I'm not sure if it will work or not. Also do I just apply it to the sides and a little inside the cap tube? This won't clog up the system correct?

[Vance R]

Nope, it's a good old boy trick. Rub your finger on your face near the corner of your nose or cheek then on the end of cap tube.

[6010fd12]

Is this a good score? I just want to make sure the opening is good before I proceed.

[Vance R]

Look fine, if your concerned just lightly file to clean up out edge then a baby ice pick or scratch awl for inside. Mainly no reduction on inside diameter.

[6010fd12]

When brazing the cap tube is it better to run the nitrogen from the high side or low side?

[Vance R]

Not sure, don't use nitrogen to braze. Thinking from the highside to keep cap tube clear since this is the normal direction of flow.