LG LFXC24726 Refrigerator icing up, won't enter Test Mode 3

Mot911

Premium Member
Joined
Aug 7, 2019
Messages
2
Location
Seattle
Model Number
LFXC24726
Brand
LG
Age
1-5 years
Hi,

I have a reoccurring problem with the refrigerator (LG LFXC24726) coils icing up, no issues with the freezer. This time the top of the compartment was much warmer (~50 deg F) than the bottom (~39 deg F), which is the first time this has happened.

Troubleshooting done so far:
1. Defrost heater resistance is good (110 Ohm).
2. Defrost sensor is good, Ohms vary with temperature in range within spec.
3. Defrost fuse seems good.
4. Insulation around the left side back panel (where the worst icing is) is not best, which could explain some of the issue. This will be improved on reassembly.
5. Main airflow fan is working OK. I will check airflow through the back panel is OK on reassembly.
6. The fan damper might have been dislodged from its hinge the last time I reassembled the back panel. Will make sure it is OK this time but it opens and closes OK in Test Mode 1 & 2.

The problem I am having is getting into Test Mode 3 to check the supply voltage to the defrost heater (Main PCB board Con 3). If I press the test button again when in Test Mode 2 the unit goes back to normal operation. I've tried with various button pushes, with Con 3 connected and disconnected etc.

Is there something I'm missing?

Thanks in advance for the help.

Cheers
Tom
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
101,322
Location
McMullen Valley, Arizona
Hi Tom,

It sounds like your control board has gone south. That's the only part it could be at this point.

Here's the main control board for your model:
Main Control Board EBR78940615


Jake
 

Mot911

Premium Member
Joined
Aug 7, 2019
Messages
2
Location
Seattle
Hi Jake,

Thanks for the quick reply. That's the conclusion I came to but was hoping for the best! Given that the drain tray in the bottom was completely dry and that fact it won't enter Test Mode 3 I guess the defrost heater may not be switching on even though the rest of the system seems to be working normally.

I'll give it some time to see if my improved insulation helps and will swap out the board next time it needs deicing.

Cheers
Tom
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
101,322
Location
McMullen Valley, Arizona
Ok Tom, sounds good.

Jake
 
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