This is an ongoing issue and I expect to replace every part on this refrigerator before I’m done :-/
The problem is the freezer temperature sensor: it measures temperature accurately (more or less) until the temp gets to about 26-28 degrees F according to the panel display. Then, it more often than not drops to -8 F and stays there, regardless of the actual temperature in the freezer.
This results in the compressor operating properly until the freezer temp goes below 26, then it shuts off until the temp rises back to 29 or so. Obviously, I don’t get any ice production unless I press the reset button, and the freezer is pretty marginal temperature-wise.
Haven’t tested the fridge temp yet but it seems OK.
At this point I have replaced the PCB and the freezer temp sensor. I ordered the sensor from APP; we had some trouble finding the part number on the diagram and the one that came had the wrong connector on it, but I was able to swap the connector from the old sensor and they are both the PCX 41 sensor so I think that’s OK (but I’d like to get the REAL sensor eventually, I’m picky that way.)
I did a slurry test on both sensors and they both read around 13,300 ohms in the slurry so I don’t think the sensor is the problem.
I have read in some places that wacky behavior like this can be caused by a marginal power supply to the PCB - does the PCB get its power from the PCB inverter? Can I test the inverter for proper voltage? (Although I think it is messing up under load which would account for intermittent behavior.)
I tested voltages and such on the PCB board and found a significant drop in when the compressor / defroster is on. It turns out that the refrigerator temp sensor is also reading different tmeps than actual (although it doesn’t peg out at -8 like the freezer one does.)
When I shut the fridge off for 10 minutes this afternoon and then started it back up, the temp sensors read accurately-ish until the compressor came on; then things went wacky again.
I think this may be the EMI Coil filter (DA27-00019) going bad. I have seen all sorts of bizarre behavior in computers when the EMI coils in a power supply start to fail.
Has anyone had experience with a coil filter going bad on a fridge and causing erratic behavior like this? I’ve searched a few appliance boards and found washers and dryers that malfunctioned strangely when the the EMI filter started to go bad.
FYI, there are multiple thermistors in the 4267. In both the freezer and fridge, there is one on the evap coil and one in the cabinet. The icemaker also has one. If they are just mis-reading you won’t get an error on the panel. You only get the error if the circuit is open (broken wire).
My problem looks to be a sealed system issue. I started replacing temp sensors on the advice of another tech - however, when I got the back panels off and looked at both evaporators, I found that there was only frost / ice for the first few inches at the top - a classic indicator of compressor / refrigerant issues. Since the freezer thermistor is mounted in that area, it reads cold while the cabinet is not cooling correctly - hence you get weird readings on the panel.
The good news is that the sealed system has a better warranty - 5 years. If yours turns out to be a compressor or evap issue take it up with Samsung!
ps - the motherboard generates its own DC for sensors and such so the EMI coil can’t be the issue. I now know a lot more about this box than I did 4 weeks ago :-/
Picture of the freezer evap below - freezer thermistor circled. The fins of the evap should have even frost all the way, you can see only the top row has frost in this case (red arrows)
Verdict: Sealed system leak on the low pressure side and weak compressor. Tech is putting an order into Samsung for replacement compressor and drier. There was a fine sheen of compressor oil on some of the pipes feeding the compressor, so the leak is most likely there. It is also possible the leak is a tiny pinhole in one of the evaporators; he is going to run a vacuum test when he replaces the compressor.
The tech was out Saturday to swap the compressor. Once they got the new one installed they ran a vacuum test on the sealed system to make sure there wasn’t a leak somewhere else.
I suppose there could still be a very tiny leak somewhere that will manifest again days or weeks from now, but the tech seemed satisfied that it was OK.
About 4 hours after they finished, it started making ice - temperatures are now correct (38F fresh, 5F freezer) and the front panel reflects reality.
All parts of the sealed system are covered by the warranty. If it’s a leak, that part is covered. Don’t let them beat you up on that. The only piece that is kind of a head-scratcher on sealed system warranty is the defrost heaters - they are riveted to the evaporators. Evaps are covered under sealed system, but heater is not - and you are supposed to swap them as a unit (although I have seem some ‘motivated’ people cut the rivets).
