LG LFX31945ST French Door low side in vacuum capillary tube issue?

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
Model
LFX31945ST
Brand
LG
Age
1-5 years
LG LFX31945ST French Door

Hi I got this 2014 used LG fridge in excellent condition the woman said it needs a compressor.
Found service valves have been brazed onto compressor suction line and high side on the filter dryer stub.
No pressure was in the system and saw dye had been added.
Used black light and saw dye in the condensate drain pan water.
Checked evaporator in fresh food section and saw dye all over the coils and dripping into drain pan.
Looked like the aluminum to copper transition crimp was the leak.
Checked freezer evaporator looked fine no sign of dye.
Ordered brand new evaporator assembly since it comes with the defrost heater and sensors and wire harness all attached so decided to go ahead and replace freezer evaporator at same time as I read the defrost heaters get weak over time and I had it all apart already.

When i removed the black tape sealant that they wrap around the brazes to cut the tubing i noticed what looked like damage to the capillary tube just above the braze it felt like someone pinched it with side cutters but looking closer it looks like a factory made pinch off crimped on the capillary tube so its like a tiny orifice made with some type of tool.

Looked at the freezer capillary tube and has the same tiny crimp mark you can feel it with your fingernail.

I wasn't sure if last person working on this did that or if it was factory made crimp.

I cut and filed and used tiny pick tool made sure cap tube was open (below these tiny crimps).

I used Stay Brite 8 to silver solder in the two new evaporators, pulled vacuum for 1 hr and charged with 134a 5 oz.

System is running low side in 20 in hg vacuum and High side 110 psi left it overnight running and fridge is hot inside.

Pulled power cord pressures do not equalize at all low side stays in vacuum with power off.

Obviously a restriction but does anyone know about these tiny crimps are they supposed to be there in the cap tubes?

Or possibly the drier is clogged maybe the last guy used sealer dye to stop the leak and clogged either the cap tubes or drier with it.

PS this is the LG that uses a reversing valve by the linear compressor to direct the flow to each evaporator.
Compressor sounds good and no flashing error led on main board and no errors on front panel.

Thanks!
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
... tiny crimp mark !
I've never seen a crimp mark in a cap tube on any machine.


....pulled vacuum for 1 hr and charged with 134a 5 oz..... low side in 20 in hg vacuum and High side 110 psi.
You missed a few things. Number one rule when doing a sealed system repair, always replace the filter drier whenever the system is opened. Don't leave the system open for very long. The oil in the compressor will absorb a lot of moisture. Before making a sealed system repair : Start with the power cord unplugged from the outlet. Plug in the power cord and between 6 and 12 seconds after it has been plugged in, unplug it from the power source. this will allow both sides of the 3 way valve to be opened to allow for proper evacuation. The 3 way valve has plastic parts inside, so always wrap it with a wet cloth before servicing when using a torch. Vacuum to 29 hg in a vacuum. Once it reaches 29 hg in a vacuum continue running the vacuum pump for an additional 20 minutes (an hour is fine). Close off the valves on the gauges and note the low side pressure (29 hg). Wait about 30 minutes to an hour and check the low side gauge. If the gauge needle moved towards 0 you have a leak. If your still at 29 hg (or very close), purge the gauge hoses and add the correct amount of R-134a and restore power to the machine. If the gauge needle goes back into a vacuum and stays there, you have a restriction.
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
Thanks Rick,
Yes I know there is some restriction for sure.
I might have soldered the cap tube shut since i used Stay Brite 8 solder which might have run down inside and up into the cap tube or that tiny crimp thing (its on both evaporator inlets) is clogged up or not even supposed to be there at all.
The cap tubes down by compressor are color coded yellow and blue i where they are coiled up near the 3 way valve.
I chatted with LG online with that pop up chat and they told me that fridge was in their system as having been recharged in Feb 2018 and system was now normal, but the lady never said that when I got his machine she said the repairman told her it needed a new compressor. LG said they had no record of compressor being diagnosed bad.

It looks like a new drier was brazed in when the guy charged it and he must have used a dye dryer thats how I found the leak.

I only had system open for 1 hr while i replaced the evaporators and pulled vacuum for 1 hr, left it overnight and she held vacuum so I charged system but as I said low side is in vaccum high side 110 psi.

I left it unplugged overnight with gauges still connected and it stayed in vacuum on low side and held 110 on high side with machine unplugged.

Have to desolder the cap tubes tomorrow and see whats going on just not sure if i should cut off those crimp sections.

I will take pics of the crimps if camera will focus on them clearly.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
OK post a few pics here and I'll take a look. I can't think of any reason to restrict the cap tube even more than what it already is. If it needed to be smaller they would have just replaced the entire cap tube and not restrict it with a crimp. Then again, we're dealing with LG so anything is possible.
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
In HVAC votech school back in 1986 my teacher taught us that Stay Brite solder was much easier to use than brazing rods and requires less heat so I have used it 95% of the time ever since and never once had any fittings fail.
The mfg says it is actually stronger tensile strength than brazing rods.

Also he taught us that when pulling a vacuum you can apply heat to the filter drier gently with low flame torch and that will cause the desiccant inside to boil off any moisture which then gets sucked out by the vacuum pump.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
.....when pulling a vacuum you can apply heat to the filter drier gently with low flame torch
Why?

rickgburton said:
Number one rule when doing a sealed system repair, always replace the filter drier whenever the system is opened.
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
I've never seen a crimp mark in a cap tube on any machine.
I posted this question on another help board and this guy replied to me.

Posted by UmmScott

YES....LG puts that pinch in the cap tubes from the factory.

From what Ive been told, they put that pinch in there so you don't hear the sound of refrigerant flowing/equalizing during the off cycle.
Lg said to remove said pinched area and that should take care of the restriction.

That was me talking to LG tech support a few years ago. Idk how i even made it that far because you're supposed to be factory authorized...etc...blah blah blah...

He said on some units they over-pinched that area and caused too much of a restriction OR something gets stuck at the pinch causing a complete blockage
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
Interesting!
Yeh I agree very interesting they would do that and its got to be my problem.
I wonder if the guy that recharged it in Feb 2018 put leak sealer in too that gummed up those pinch offs in the capillary tubes.
When I take it back apart I will update my findings and take some pics.
Thanks for your advice and tips etc.

When you replace driers do you always use OEM ones or are the generic ones ok too.
I see Supco and another brand Smart Electric make very reasonably priced generic driers with the service valve stubs a fraction of the price of the LG part number.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
I use the Supco D111. Be sure to remove the valve stem before brazing it in. I don't use any leak sealer. I think it does more damage than it does good but that's just my opinion. I've used the filters with the dye inside to find a small leak but that usually takes a while before they call me back. These are leaks that takes 6 months to a year before they leak enough refrigerant to start losing the cooling. 99% of the time these end up being leaks in the aluminum evaporator.

I found this video by chance, looking for the part number of the filters I use:
[video=youtube_share;K8MytWJQHZg]https://youtu.be/K8MytWJQHZg[/video]
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
I think the 3 way valve is defective.
I de-soldered the cap tubes and put compressed air on the high side and the freezer cap tube blows strong but fridge was very weak flow.
Re-soldered them up ran vacuum for over an hour.
The filter drier is marked UV Drier so that was replaced in Feb 2018 (confirms what LG told me about this serial number that it was recharged and cooling normally).
When I recharged it the pressures were normal about 2 psi low side 100 hi side and freezer was cold overnight but fridge was barely working evaporator was slightly cool to the touch.
Watched the pressures and occasionaly low side drops into about 20" vacuum so I assume that is when it tries to flow to the fridge evap and it either jams up the valve or the cap tube is plugged up.
So either the cap tube is plugged up or the 3 way valve is only allowing flow to the freezer.
I was going to cut the 3 way lines and just bypass the valve recharge it see if they both cool before investing $120 in a 3 way valve.
The solenoid it clicking on the valve actuator when I plug it in you can feel it trying to operate the 3 way valve but I read on these forums the internal valve jams up.
What would happen if I just bypass it and leave it piped for constant flow to both evaporators?
Will the fridge start giving error codes since it cannot vary the temps?
If I set the set-points to the coldest settings for both freezer and fridge would that prevent it from setting codes?
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
Start with the power cord unplugged from the outlet. Plug in the power cord and between 6 and 12 seconds after it has been plugged in, unplug it from the power source. this will allow both sides of the 3 way valve to be opened to allow for proper evacuation. The 3 way valve has plastic parts inside, so always wrap it with a wet cloth before servicing when using a torch. Always replace the 3 way valve if there is a leak at any one of the 3 tubes coming from it.
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
Start with the power cord unplugged from the outlet. Plug in the power cord and between 6 and 12 seconds after it has been plugged in, unplug it from the power source. this will allow both sides of the 3 way valve to be opened to allow for proper evacuation. The 3 way valve has plastic parts inside, so always wrap it with a wet cloth before servicing when using a torch. Always replace the 3 way valve if there is a leak at any one of the 3 tubes coming from it.
I just found a LG training document and it explains that if you put this fridge in Test Mode 1 it opens the 3 way valve and flows to both evaporators so I will play around more with it before trying to bypass it or replace the valve.

It seems that those 3 way valves are problematic on LG and Samsung i guess they have not worked out the kinks in this dual evap system I think they need a bigger valve assy that is more reliable than these tiny valves that probably clog up.

LG dual evaporator training document and other LG appliances from a 2011 class I believe

https://www.dropbox.com/s/e2ctsnpofl3ra5p/lg_fall2011_ha_trainingmanual.pdf?dl=0
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
From LG dual evaporator training manual

NOTES
Before attempting sealed system repair – initiate TEST MODE STEP 1
(88 88). This will open 3 Way Valve to both evaporators – unplug 3 way
valve harness from chassis connector.
OR
Plug Refrigerator into outlet – wait 6 to 12 seconds – unplug power cord &
unplug 3 Way Valve Harness from chassis connector.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
33,119
Location
Murray, Utah 84107, United States
Thanks for the manual! OK, if you have lots of time and two pair of pinch off pliers you can test each evaporator individually but that's a lot of cutting and brazing. I don't see any other way to bypass the three way valve. The refrigerator evaporator has higher pressure so there's a pump down mode and both cap tubes are closed off and the extra refrigerant in the fresh food evaporator is stored in the condensor. You bypass the 3 way valve and that doesn't happen.
 

Houptee

Premium Member
Joined
Aug 18, 2018
Messages
17
Location
NEW JERSEY
Yep I read that in the training manual about the pump down sequence.

I was hoping the way it would work if I removed the 3 way valve would be the inverter compressor would vary its speed when the two evaps reached set point vs the 3 way valve changing the flow of refrigerant to each but guess it would never work right and it would not be able to control the temp in each compartment and probably get too cold in fridge with constant flow all the time.
 
Top