Older LG Minisplit Decision time

Bben

My LG unit LG (LSN240HSV2) was discontinued in 2014 and has R-410A refrigerant. It shows oil leaking at line-sets in attic, drips water on floor in AC mode and reduced heat flow in heat mode.
Plan A:
Remove refrigerant. (Pump out and weigh).
Positive pressure nitrogen test to 500 psi.
Negative pressure vacuum cleaning. Below 500 microns.
Weigh back in factory charge and add UV dye kit/leak stopper.

Since line-set shows oil at back of unit in attic do I need to redo all the line-set flares (in and out)? Line sets run inside wall to outdoor unit so difficult to replace unless run outside of house.) Is is possible oil leak is from unit itself and is running down the line-set? (Oil is around the flares but kinda hard to tell.)

Plan B: Time for new unit?
Thanks for your advice.

pecmsg

Do NOT use leak stop.
Is this the pre-insulated line set? There were serious issues with them.
Discontinued means parts no longer available, replace the entire system, indoor, outdoor and lineset.

Bben

Pic of attic line-sets:

pecmsg

Is the line set leaking or the flair joints?

Bben

Near as I can tell its the flair joints.

Bben

The line sets have black foam insulation on them so not the preinsulated kind.

Bben

Also saw these flare seals (on Amazon) that you apparently place inside old flares to stop leaks. And thanks for your response, pecmsg.

pecmsg

Then the joints need to be leak checked. Simple dish soap water down and brushed on the fittings. If they bubble time to redo. Not a DIY project at that point.

Bben

Thank you! Dish soap on hand! Assume unit needs to be running to check. AC or heat mode matter?

pecmsg

Start the system in heat and run for a few minutes. Kill the power to the outdoor unit, the lines will remain pressurized.

Bben

Thanks again. I'm assuming the stop leak is like that junk we used to put in radiators and therefor bad?

pecmsg

Minis use very fine screens, that crap plugs them up.

Bben

Couple of questions on pressures. Sticker on outdoor unit says low side pressure design pressure of 240 PSIG pressure (high side pressure 450 PSIG). Manual says pressure range of 120-135 PSIG at outside ambient temperature of 95 degrees F. I’m assuming I can check for pressure at 240 when NOT running in cooling mode. Then check pressure WHEN running to between 120-125 . Outside temperature now 40 degrees. Thanks for your thoughts.

mattmia2

Those pressures are test pressures for leak testing. To check the charge you need to measure the subcooling.

Ceacel

inverter ?
no subcooling. 

Weigh out, compare to factory charge. 

Pressure/bubble test with big blue, remake flares as needed. 

Evacuate
weigh factory charge back in.