LG LMXC23746S Fridge not cooling

[6010fd12]

Long story short. Bought this fridge as not working from someone for $100 in hopes that I could learn how to repair a fridge and if successful I could use it. I have very basic HVAC knowledge and experience from replacing car compressors and refilling refrigerant. The story from the owner was that the compressor was replaced 2 or 3 times with the final time the compressor only lasting overnight? before lg finally gave up and gave him a partial refund.

What I noticed after taking home the unit and waiting a day before turning it on was that the compressor and condenser fan were running but the fan inside the fridge was not. Even with the compressor running the liquid line was not getting warm. I understand that there have been problems with the old compressors on these models but this one was replaced with the newer model and the pcb has been updated with the newer firmware (as noted on the sticker).

I am trying to figure out what's wrong here. If the compressor really did fail again or if there is maybe a leak in the system. But if all the refrigerant did leak out then wouldn't the compressor not kick on? (This is the part where I have no clue what I'm doing) I have hooked a low side guage up to the service port that luckily was left my the technician to try and see if there was maybe suction on the low side but the needle stayed just above half a psi and went down to 0 when the compressor kicked on. Any ideas?

[ECtoFix]

I can't answer your direct questions, but will try to guide you to some relevant info available on the world wide web.  I don't do residential refrigerators.  Just commercial.  Funny that I find myself saying that because..although commercial refrigeration equipment is MUCH more expensive to purchase and repair, it's also FAR simpler in design than what you got there for $100. You picked a doozy of a refrigerator to learn from. 

From what little I've read on LG units within that family of...refrigerators, they have DUAL evap coils instead of a typical SINGLE coil.  They have a (unusual) three-way valve, an unfortunately a mix of copper-to-aluminum junctions in the refrigeration system (difficult to properly braze for the inexperienced) , a check valve (something generally only found in HVAC heat pumps), multiple capillary tubes (any of which are prone to clog), that linear compressor (which I've never encountered before) ...and I'm sure there's more I could find if I was willing to spend several hours on the internet researching it.

ALL of the aforemented (and yet to be mentioned) can have you delving into challenges WELL beyond anything that your very BASIC HVAC/R training covered. 

However, FWIW - I can share these tidbits of info:

• Google your model number.  There's a service manual there to found by doing so.
• Here's an LG training manual which covers dual evap systems to some depth: https://applianceassistant.com/ServiceManuals/lg_fall2011_ha_trainingmanual.pdf

Off the cuff, I'd say that your suction pressure is too low (for a warm box) and the evap fan isn't running because the DTFD (defrost termination-fan delay) control didn't get cold enough to kick the fan on (normally around 20°).

AGAIN  this is all from a guy with COMMERCIAL refrigeration experience.

 

[6010fd12]

1 hour ago, ECtoFix said:

I can't answer your direct questions, but will try to guide you to some relevant info available on the world wide web.  I don't do residential refrigerators.  Just commercial.  Funny that I find myself saying that because..although commercial refrigeration equipment is MUCH more expensive to purchase and repair, it's also FAR simpler in design than what you got there for $100. You picked a doozy of a refrigerator to learn from. 

From what little I've read on LG units within that family of...refrigerators, they have DUAL evap coils instead of a typical SINGLE coil.  They have a (unusual) three-way valve, an unfortunately a mix of copper-to-aluminum junctions in the refrigeration system (difficult to properly braze for the inexperienced) , a check valve (something generally only found in HVAC heat pumps), multiple capillary tubes (any of which are prone to clog), that linear compressor (which I've never encountered before) ...and I'm sure there's more I could find if I was willing to spend several hours on the internet researching it.

ALL of the aforemented (and yet to be mentioned) can have you delving into challenges WELL beyond anything that your very BASIC HVAC/R training covered. 

However, FWIW - I can share these tidbits of info:

• Google your model number.  There's a service manual there to found by doing so.
• Here's an LG training manual which covers dual evap systems to some depth: https://applianceassistant.com/ServiceManuals/lg_fall2011_ha_trainingmanual.pdf

Off the cuff, I'd say that your suction pressure is too low (for a warm box) and the evap fan isn't running because the DTFD (defrost termination-fan delay) control didn't get cold enough to kick the fan on (normally around 20°).

AGAIN  this is all from a guy with COMMERCIAL refrigeration experience.

I've actually been talking with someone on reddit about this and he believe that there is a restriction. I hooked up some gauges and here are the readings that I got. Video

I might now know much about HVAC but that high side definitely looks low to me. I wanted to know what your thought were on this. I understand you only deal with commerical systems but any point in the right direction would be extremely helpful. I have ordered a recovery system so I can see if the system is actually full or is missing freon and if it's not I will most likely try to install a new condenser in or a 3 way valve like I was suggested on reddit. I don't own a nitrogen system so right now thats out of the question.

[ECtoFix]

You're out of refrigerant.  Definitely a low charge - either from a leak or poor repair practices.  I'd say a leak since NO tech would leave it like that.

You will need to find that that leak.  Pressurize with nitrogen and a bubble test w/visual inspection is how I've always done it.  An electronic leak detector can get you in the ball park, but only that.  Still gotta narrow it down with a visual inspection or bubbles.

There's no other ways other that a dye and test with a UV light.  I never liked that method.  Messy.

[6010fd12]

6 minutes ago, ECtoFix said:

You're out of refrigerant.  Definitely a low charge - either from a leak or poor repair practices.  I'd say a leak since NO tech would leave it like that.

You will need to find that that leak.  Pressurize with nitrogen and a bubble test w/visual inspection is how I've always done it.  An electronic leak detector can get you in the ball park, but only that.  Still gotta narrow it down with a visual inspection or bubbles.

There's no other ways other that a dye and test with a UV light.  I never liked that method.  Messy.

THANK YOU! THIS WAS MY EXACT THOUGH PROCESS! I was so confused by what the person on reddit was saying about a restriction it just didn't make sense to me. If there really was a restriction on say the condenser I would think that most of the refrigerant would be trapped on the high side and there would be vacuum on the low side as the compressor was trying to suck in refrigerant. It just made a lot more sense to me that since the high side pipe wasn't getting hot and the pressure reading was low on the high side that I was most likely missing refrigerant. I just didn't want to start adding some willy nilly without knowing how much was in the system. This makes me so happy to hear that! Honestly I am very thankful that you could confirm my suspicions. Now I just need to wait on that recovery system to see if it is true.

[ECtoFix]

BTW:

Don't run that unit anymore until you know where the leak is at. 

If on the high side, you can repair the leak using a torch (with nitro flow), leak test, evacuate & recharge - hopefully with no anticipated problems.  All that beings that the high side has remained above atmospheric pressure during operation.

If the leak is on the low side and it's operated in a vacuum, then the compressor oil is screwed.  With it having POE oil (used with R134A systems), that stuff is hygroscopic and sucks up moisture more than a sponge.  So, if you don't change the oil, flush the system and replace the oil - it will become acidic and the refrigerator might last a just a few years at best.

[6010fd12]

4 minutes ago, ECtoFix said:

BTW:

Don't run that unit anymore until you know where the leak is at. 

If on the high side, you can repair the leak using a torch (with nitro flow), leak test, evacuate & recharge - hopefully with no anticipated problems.  All that beings that the high side has remained above atmospheric pressure during operation.

If the leak is on the low side and it's operated in a vacuum, then the compressor oil is screwed.  With it having POE oil (used with R134A systems), that stuff is hygroscopic and sucks up moisture more than a sponge.  So, if you don't change the oil, flush the system and replace the oil - it will become acidic and the refrigerator might last a just a few years at best.

Gotcha. I don't own any nitrogen so letting some UV R134a into the system and cycling the compressor for a while would be the way to go or to just use the leak detector correct? I just don't understand how I can accomplish it without turning on the compressor. So right now what do you think my plan of action should be. Sorry again I don't work in HVAC so you might explain this to me like I'm 5.

[ECtoFix]

31 minutes ago, 6010fd12 said:

I don't own a nitrogen system so right now thats out of the question.

4 minutes ago, 6010fd12 said:

I was so confused by what the person on reddit was saying about a restriction it just didn't make sense to me. If there really was a restriction on say the condenser I would think that most of the refrigerant would be trapped on the high side and there would be vacuum on the low side as the compressor was trying to suck in refrigerant.  It just made a lot more sense to me that since the high side pipe wasn't getting hot and the pressure reading was low on the high side that I was most likely missing refrigerant.

I stated what I did under the assumption that your gauges were INDEED correctly connected.

33 minutes ago, 6010fd12 said:

I don't own a nitrogen system so right now thats out of the question.

That's an essential tool for HVAC/R.  The bottle, a regulator and the contents from your local supply house.  About $150.00 maybe?

[6010fd12]

2 minutes ago, ECtoFix said:

I stated what I did under the assumption that your gauges were INDEED correctly connected.

That's an essential tool for HVAC/R.  The bottle, a regulator and the contents from your local supply house.  About $150.00 maybe?

Hum. Ok I will try to get my hands on that. I just can't find a small cheap container online anywhere. The cheapest one I can find is $170 and thats without guages unless I'm looking at the wrong thing. Do you have any suggestions where I can get my hands on a set for $150 like you mentioned?

[ECtoFix]

4 minutes ago, 6010fd12 said:

I just don't understand how I can accomplish it without turning on the compressor.

The dye would need to be added with a charge. To ME, adding a dye is an act of desperation since other leak detection methods are preferable.

In that unit's present state, it's best to pressurize with nitrogen and squirt some Big Blu at suspect joints/components.  I've heard the evap coils on those LG refrigerators a prone to leakage.

[ECtoFix]

8 minutes ago, 6010fd12 said:

The cheapest one I can find is $170 and thats without guages unless I'm looking at the wrong thing.

No, you're not looking for LIQUID nitro!  Heck NO! 

Just a bottle with gaseous dry nitrogen in it.  Much like a SCUBA tank of the stuff.  Typically charge to 2000 psi.    20 or 40 Cu.Ft.  Has to be purchased locally.

Then a regulator. 

Do NOT attempt pressurizing a system without a regulator!  My former supervisor's instructor (back in the '60s) got his HEAD blown off due to that man's lack of using a regulator!

Try United Refrigeration or JohnStone Supply.

 

[ECtoFix]

24 minutes ago, 6010fd12 said:

The cheapest one I can find is $170

...and what you're looking at THERE is just a container.  Nobody is going to ship you a container with nitro already in it.  Too much PSI.

Call me a BOOMER, but that's how I understand it.

[6010fd12]

2 minutes ago, ECtoFix said:

No, you're not looking for LIQUID nitro!  Heck NO! 

Just a bottle with gaseous dry nitrogen in it.  Much like a SCUBA tank of the stuff.  Typically charge to 2000 psi.    20 or 40 Cu.Ft.  Has to be purchased locally.

Then a regulator. 

Do NOT attempt pressurizing a system without a regulator!  My former supervisor's instructor (back in the '60s) got his HEAD blown off due to that man's lack of using a regulator!

Try United Refrigeration or JohnStone Supply.

 

Yikes! Ok gotcha. I think I might have found a welding store near me that might sell some. After I purchase the nitrogen how do I proceed? I'm assuming first I recover the system and then pressurize the high side first to (50 psi? or some low number) and spray that liquid all over to try and pinpoint a leak?

[Vance R]

There is probably already has a dye drier in the system. Hard to tell from video but it looks like a ADH73150210 drier is being used. The ends of the tubing on the drier come pre-swaged to make installing easier.  use a mirror to look for the printing UV DYE. You can get light and glass from auto parts store. Someone used lokrings to install the compressor - potential leak spots.  Since your gauges read near 0 psi with system off your system is empty or nearly empty.  Need to find the leak before moving on.  If you can't get nitrogen, just use alittle refrigerant it is probably a large leak if it didn't last a day.

[ECtoFix]

With your perceived charge being so minimal, that almost qualifies as a tracer charge (enough for an electronic leak detector to sense).  Your efforts to recover that lille amount would amount to nothing.  So, just put the nitro in with the refrigerant.

Here's an EPA guide on leak detection:

https://www.epa.gov/sites/production/files/documents/RealZeroGuidetoGoodLeakTesting.pdf

[ECtoFix]

@6010fd12,

read what @Vance R says.  He's far more familiar with those units than I am.

[ECtoFix]

9 minutes ago, Vance R said:

just use alittle refrigerant it is probably a large leak if it didn't last a day.

I didn't even think of that!  Yup, that would be simpler.

My thinking is from habitually using nitro without any reservations, but having to account for every stupid ounce of refrigerant I used (YES - we did that!).

[Vance R]

These refrigerators usually  use 4.76 or 5.11 oz of refrigerant. Lots of small amounts to track.  Hoping the leak is not one of the lokring fittings. No fixing,  just cut it off and hope there is room to braze on a repair section.

[6010fd12]

49 minutes ago, Vance R said:

There is probably already has a dye drier in the system. Hard to tell from video but it looks like a ADH73150210 drier is being used. The ends of the tubing on the drier come pre-swaged to make installing easier.  use a mirror to look for the printing UV DYE. You can get light and glass from auto parts store. Someone used lokrings to install the compressor - potential leak spots.  Since your gauges read near 0 psi with system off your system is empty or nearly empty.  Need to find the leak before moving on.  If you can't get nitrogen, just use alittle refrigerant it is probably a large leak if it didn't last a day.

Yup! You are right on the money with that one! So the next step is to use a UV light and look all around the fittings and pipes correct?

[Vance R]

Yes and pull the defrost drain tubes. Look in the duckbill valves for dye from the evaporators. 

[6010fd12]

13 hours ago, Vance R said:

Yes and pull the defrost drain tubes. Look in the duckbill valves for dye from the evaporators. 

https://youtu.be/FLpCY5gAMhg

How do I go about cutting off the lokrings? I was thinking a hacksaw so I can was close as possible to the fitting but I dont know if that's a good idea since metal shavings might get into the line. Also I'm assuming I have to vent the system first since it does have 3-4 psi of refrigerant left before working on it?

[Vance R]

Tough call, tubing cutter would be best. You will need tubing long enough to make new joints. Use what you have on hand and that will preserve tubing length.  Now about the lokring fittings - there should have been some sealant used to help prevent leaks. The sealant is a blue color and cures in less than 10 minutes. Got curious and took some pictures. One is just plain lighting, the sealant is a blue green color. The other picture is with uv light and using the glasses over the lens, it is kinda still blue green with a yellow tint.  From your video, there is always some spray from connecting and disconnecting hoses. That color seems to be the same for all the suspected leak areas. Usually when using the sealant you use just a couple of drops per side. So the large area under the suction line is probably a drip.  Did the joints feel oily? Also the condenser is probably new, hard to tell from video, but there are lokrings on both ends of the condenser. The factory fitting on the output side of condenser if different. So you are correct about the spray causing dots.

More than likely little to no refrigerant left in the system.  What is in the system is air or non condensables.  Before you work on the system you will need to open the 3-way valve to both evaporators.  2 ways to do this procedure. First is to plug in refrig and wait 6 seconds and unplug before 12 seconds has elapsed. During the first 6 seconds you can feel the 3-way vibrate twice.  Second is to plug in the refrig and push the daig button on the main board. This will place the refrig in the forced mode step 1, compressor will ramp slowly to 100% capacity, all fans will be turned on. After about a minute just unplug. 

[6010fd12]

On 5/25/2020 at 3:46 PM, Vance R said:

Tough call, tubing cutter would be best. You will need tubing long enough to make new joints. Use what you have on hand and that will preserve tubing length.  Now about the lokring fittings - there should have been some sealant used to help prevent leaks. The sealant is a blue color and cures in less than 10 minutes. Got curious and took some pictures. One is just plain lighting, the sealant is a blue green color. The other picture is with uv light and using the glasses over the lens, it is kinda still blue green with a yellow tint.  From your video, there is always some spray from connecting and disconnecting hoses. That color seems to be the same for all the suspected leak areas. Usually when using the sealant you use just a couple of drops per side. So the large area under the suction line is probably a drip.  Did the joints feel oily? Also the condenser is probably new, hard to tell from video, but there are lokrings on both ends of the condenser. The factory fitting on the output side of condenser if different. So you are correct about the spray causing dots.

More than likely little to no refrigerant left in the system.  What is in the system is air or non condensables.  Before you work on the system you will need to open the 3-way valve to both evaporators.  2 ways to do this procedure. First is to plug in refrig and wait 6 seconds and unplug before 12 seconds has elapsed. During the first 6 seconds you can feel the 3-way vibrate twice.  Second is to plug in the refrig and push the daig button on the main board. This will place the refrig in the forced mode step 1, compressor will ramp slowly to 100% capacity, all fans will be turned on. After about a minute just unplug. 

I'm going to try the pipe cutting method. Would this work well for brazing the pipe afterwards?  Also how do I go about letting the nitrogen flow through the system while brazing?

[Vance R]

Nope, sil fos 15 for copper to copper, Harris Safety-Silv 45% with flux for copper to steel. If want to use nitrogen this the flow reg i use. Uniweld NV1 NitroVue Nitrogen Flow Indicator 1/4"F X 1/4"M.  

[6010fd12]

1 hour ago, Vance R said:

Nope, sil fos 15 for copper to copper, Harris Safety-Silv 45% with flux for copper to steel. If want to use nitrogen this the flow reg i use. Uniweld NV1 NitroVue Nitrogen Flow Indicator 1/4"F X 1/4"M.  

Gotcha. I ordered the flow indicator and did some research. So basically I need to take the schrader valve off both high and low sides and have the nitrogen flow from one side while I braze. Also would these work? Harris and SLIFOS15(however it's telling me that the item is discontinued). If for some reason I need extra tubing what do I search to find it at my local big box stores?

I wanted to ask 2 questions. Do I need to worry about the oil inside the system at all? Or when should I be concerned it?

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