Testing my LG FMA102NBMA refrigerator compressor.

[Velkomen]

Hello - my LG refrigerator linear compressor does not turn on (LG fma102nbma).  When I checked the resistance across the three compressor pins I had zero, zero, and 16.6 ohms. Does 16.6 ohms indicate a malfunction? I was expecting a value like 7.5 ohms from information from the web. 

[EngineeredAppliance]

Hi I suggest going back a few steps. If your compressor isn't starting this doesn't mean the compressor is bad. You could have a control issue. If you were to remove the PCB cover panel. Do you have any red lights blinking? If so how many times does it blink? Have you initiated the test button? If so did the compressor turn on at all? You see there are many steps to troubleshooting this issue before jumping to the compressor. A liner compressor typically operates on two pins. Power and common. You should check there typically between 5.1-6.3 ohms. You should also check those pins to earth to check for a grounded compressor. Even though LG has known compressor issues. You should not skip ruling out the control portion first. Thermistors, Control board, and Inverter. Caution These compressor operate at high voltage 80VAC -230VAC. If you are not comfortable working with high voltage or competent using a meter I would suggest calling a professional. If you would like more advice feel free to reply. 

[Jorgem]

Hello, I am fixing same refrigerator. I have also done the pin test. Looks like it only works on 2 pins. I thought it would be like other models where all 3 pins had to show same Ohms. The board clicks and red light flashes 3 times. Same exact model. I am trying to determine the problem. I have checked current from board pins going to compressor I’m reading 300 and something not sure what that means. Any ideas? Have you fixed this problem?

[Richbahama]

Having the same issue with a LRFCS2503S/00 unit, three flashes on PCB unit, going to meter out the compressor now to see what readings i am getting

[Howdy979]

Anyone ever get this issue resolved. If so enlighten us please.
Service manual says the refrigerant is 134a the refrigerator tag says it’s r600a and the compressor doesn’t say at all.

[Terry Carmen]

19 hours ago, Howdy979 said:

Service manual says the refrigerant is 134a the refrigerator tag says it’s r600a and the compressor doesn’t say at all.

Going by the explosion/fire warning symbol on the compressor, I'm going to say R600a.

[nano69an]

On 1/9/2022 at 5:30 PM, Velkomen said:

Hello - my LG refrigerator linear compressor does not turn on (LG fma102nbma).  When I checked the resistance across the three compressor pins I had zero, zero, and 16.6 ohms. Does 16.6 ohms indicate a malfunction? I was expecting a value like 7.5 ohms from information from the web. 

Hi, did you confirm the issue with your compressor at 16.6 ohms? how your fridge was repaired? Replacing the compressor?

I have the same compressor with 21 ohms not turn on and PCB LED blinks 3 times. Thanks.

[Jmax]

before measuring resistance at compressor. you should check that power is going to the compressor. usually 120v AC at the start device relay. then check that your start relay is good by doing continuity test or you could shake it to see if the link inside of is broken. a broken link will give you rattle sound when you shake it. if compressor has an inverter, you must check you are getting both 120 AC volt and the pulse modulated signal(3-7 V DC) from the main board at the inverter. 

[Terry Carmen]

11 hours ago, Jmax said:

should check that power is going to the compressor. usually 120v AC at the start device relay. then check that your start relay is good by doing

LG refrigerators don't have a 120 volt compressor or a start device.

[nano69an]

12 hours ago, Jmax said:

before measuring resistance at compressor. you should check that power is going to the compressor. usually 120v AC at the start device relay. then check that your start relay is good by doing continuity test or you could shake it to see if the link inside of is broken. a broken link will give you rattle sound when you shake it. if compressor has an inverter, you must check you are getting both 120 AC volt and the pulse modulated signal(3-7 V DC) from the main board at the inverter. 

See the attached snapshot of the service manual. I could not measure the resistance at point A and B but was able to remove the connector to the compressor to measure its resistance. 

As Terry stated, I couldn't find the start device.

[nano69an]

4 minutes ago, nano69an said:

See the attached snapshot of the service manual. I could not measure the resistance at point A and B but was able to remove the connector to the compressor to measure its resistance. 

As Terry stated, I couldn't find the start device.

Attached picture shows the steps taken for 3 blinks LED.

I just want to confirm that the failure is the compressor. So I will pay LG flat rate repair. Don't want to pay over $400CAD for repair to replace a cheap part like the start device.

Any help will be appreciated. 

[Rich Armstrong]

On 8/12/2023 at 4:28 PM, Howdy979 said:

Anyone ever get this issue resolved. If so enlighten us please

I just replaced the board on one of the LG refrigerators with R-600. I was also getting a 3 flash LED error. Con 201 had less the 5 Vac powering the compressor. The new board was obviously a board that had been returned judging by the wrapping. Popped the new board in with the same results as before. 3 flash LED < 5Vac output with 120 Vac verified input. I apologized for failing my customer and walked out  with my tail between my legs. 
 

The next day I diagnosed another LG. This time it was a failed compressor. Which will be my first compressor replacement.  I did measure 150 Vac at Con201. Did I install a bad board on the first LG? I’ll never know, that’s a road I refuse to go down! 

[consumer24]

LG LRDCS2603S
Refrigerator Compressor Start Relay Thermistor
 

Can someone help me find this part number and where I can order it?

[Budd023]

I have same problem. The compressor needs replacing in my case. The the 3 flashes from the board indicates compressor is not running. Why, is what you will need to test. My model is the LG LRFCS25D3 with the FMN102NBMA compressor. Where I went down the wrong rabbit hole is that you will find sites that say LG Linear compressors only have one winding to test and to test if board ramps up to 200volts in test mode. Well my linear compressor does have three points (common, power, and save) to check. Make sure to check the schematic of your fridge. Find the compressor on schematic. If it has three wires going to it and three wire on compressor you should have an ohm reading across all three. If schematic shows only two wires going to it and only two wires on compressor then only an ohm reading across those two. Be sure to check contacts to ground also. My board does not ramp up to 200V AC. The new board I bought didn't either, my guess is that it looks for signal back from compressor it is running and ramps as needed.  Hope this helps someone not go down same rabbit hole I did with thinking board is bad since didn't ramp up to 200V AC.