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lights would blink temp i replaced therm. fuse in freezer took care of problem hope this helps
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Happy,
I have found a couple of Samsung training manuals that explain how the logic works. At least, by reading them, I can tell the control design. Actually, the functions of the design are great. The implementation leaves consumers aggrravated because most refrigerator mechanics are mechanics, not integrated systems experts. eg. The self test diagnostic routine, that activates when the power fails, checks all the thermistors, (including the one on the ice maker, and which is not critical) for resistance. If any fails, it just halts. While halted, the contents rot if the operator is not there to override the error condition. That would be a simple software fix in the eprom, but Samsung is silent on the glitch leaving users frustrated and ready to junk the above average quality units.
There is a thermistor on the evaporator coil that is checked to determine when to turn off the defrost cycle. The logic also includes how many times the door was opened as well as hours the compressor has been running.
There are at least 6 thermisors on the side by side units. They are all the same with different hook-ups. Just to run up the parts list, I presume??
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Originally Posted by: chuckiejones  Happy,
I have found a couple of Samsung training manuals that explain how the logic works. At least, by reading them, I can tell the control design. Actually, the functions of the design are great. The implementation leaves consumers aggrravated because most refrigerator mechanics are mechanics, not integrated systems experts. eg. The self test diagnostic routine, that activates when the power fails, checks all the thermistors, (including the one on the ice maker, and which is not critical) for resistance. If any fails, it just halts. While halted, the contents rot if the operator is not there to override the error condition. That would be a simple software fix in the eprom, but Samsung is silent on the glitch leaving users frustrated and ready to junk the above average quality units.
There is a thermistor on the evaporator coil that is checked to determine when to turn off the defrost cycle. The logic also includes how many times the door was opened as well as hours the compressor has been running.
There are at least 6 thermisors on the side by side units. They are all the same with different hook-ups. Just to run up the parts list, I presume?? since you have this manual i have a few questions. [FONT="]freezer works great, fridge freezes up to a solid chunk of ice, and have to turn off and let it defrost for a few days, have to do this once a month. I can put it into manual defrost and it does work and turn itself off when it hits about 60 degrees and thermistor has proper resistance readings at 18k ohms (frozen) it allows manual defrost, then around 6.3 k ohms (approx room temp)it shuts off the manual defrost power while the still beeping on the defrost cycle.. because the manual defrost works and shuts off it shows all driver chips,fuses and relays are ok, is the only other thing it can be the timer board chip firmware? Or is there another input that i have overlooked. Is there a trick/backdoor to re-initialize this chip? TMP87CC40N by toshiba. I notice the low power reset is a fairchild KA7533 and that samsung did not follow suggested guidelines of a pull up resistor on the output to the reset on the toshiba chip. this low power notification chip stops the main chip when power drops to critical levels from losing execution steps (we call that la-la land). Maybe the chip is going into consistent la-la land (not likely to be consistent) with voltage fluctuations (this fridge is in Mexico) I do not own any type of data logger to watch this voltage over a fewdays or a few hours. Any feedback on this would be appreciated. fan kicks on when so not that either. this product worked fine for 3 years. as a easy backdoor patch/band-aid, I am thinking of putting in a resistor in series with the defrost sensor to shift the time on the defrost cycle to be longer since it could be that it just does not stay on long enough could be a cheat. I will probably try 2k ohms to start. By the samsung appendix I chart, this would shift from 66 degrees to 85 degrees when it shuts off assuming the auto defrost uses the same threshold as the manual threshold maybe clearing the remaining ice to solve the issue.[/FONT]
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I put a 2.2k ohm resister in series as I said I was going to do. It now has an error code on fridge start up of 3, so this defrost coil temperature sensor is probably calibrated to the regular fridge one.
But it worked as I anticipated when I did the manual defrost. It certainly allowed the heater to stay on much longer heating the entire mechanism to a much higher temperature, i hope enough to melt the ice. I did notice before the cold side of the coil did not really get very warm on the manual defrost. Right now they do.
I will do some more testing, maybe a 1k ohm resister would suffice. if one had 5 of these refrigerators with the same problem it might be easy to determine a good value.
the tradeoff is by having it heat up too much it could overheat the heater element or the thermal fuse. so the lowest resistor possible is the best one.
I had to use a surface mount resistor as that is all i have on hand. soldering those to a wire is not exactly easy. so till i make it to the bigger town will not be able to try the 1k resistor. [FONT="][/FONT]
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I will not know the outcome of my test for 1-2 months. the fridge is maintaing a proper temperture, it is working right now. it was freezing up in 30 days.
I also added a piece of aluminum sheet metal to the lower heater coils to the drain to see if that was the problem.
I have a second one of these samsungs doing the same thing freezing up , i will check the resistances in the next week. and do some testing to try to isolate the problem faster.
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my 2.2 Kohm resister "fix" (some may say hack job) appears to be working, I am 6 weeks later and it has not frooooozen up in that time. So when I hit 2-3 months I will post pictures of what I did, I also made a drain heat pipe out of aluminum flashing to conduct heat from the heat coils to the drain area.
so my symptoms were it kept freeing up to a solid chunk so the temp in the fridge was 40-60 degree. this took 3-4 weeks before I had to remove everything and do this manual defrost. everything worked in sensors and such but it kept freezing up.
as a back-up though I have not installed it i purchased on the internet bidding site a cable drain heater gemline GH204 75 watts 115 volts.
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Rank: Member
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Rank: Member
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so my tweeks have now worked for 7-8 months. adding the heat diffusers and the resistor in series to the thermostat to change the shut off temperature of the defrost cycle. Have not had to unplug the fridge for 3 days it needed to defrost it it took each time... if you are logged in you can see the photos i made in the posts.
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That is great that you figured out how to fix the poor design from the Samsung engineers. That same thermistor gave me fits for about an entire year, until I finally removed it and put it in some ice water and noticed that it stayed at 2k all the time. Never saw a thermistor do that. I opened up the white housing and found a small bead embedded in silicone rubber type stuff. peeled all the silicone away and the thermistor still wouldn't move. Ordered a few spares from a distr on line. First replacement worked for a few months then the same icing occurred. Replaced it with the second one and it has been fine for 3 years now. There must be some problem with the part or the way they encapsulate it. There is only one milliamp going through it so who knows why some fail.
I noticed on a British forum that the white thermistor is being replaced but a black part and it seems to solve their defrost problems. I have found complaints on the Samsunge fridges dating back to 2005. we got ours in 2006.
I went as far as trying to design a circuit to circumvent the cpu and use a circuit to enable the defrost heater every day for about 20 mins. But things are too complicated in these units. You have to stop the evap fan and turn off the compressor before you go into defrost. The evap fan is DC and has a sensor that senses speed. So if you turn it off when the cpu knows it should be on, the system re-initializes. So I gave up the idea and finally got a repair manual and figured out that the defrost mode would never turn on because that bad thermistor was reporting back that the evap coil was already at 120 deg. I could not even force a defrost cycle because of that thermistor. I have read about so many people that put the fridge out on the curb because they couldn't get them fixed. I went through two repair techs before they wouldn't come out anymore. Most companies I called would not touch Samsung products because of no factory support.
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this will be my last update unless there is a future problem, but it is now 10 months and not one coil freeze up. so my resister change and adding heat diffusion works and did not make a new and of life problem. so my fridge that was freezing up about every 3-4 weeks for no reason no longer has the block of ice problem.
and note my thermistor was working exactly as the chart shows in the tech manual. My fridge everything was working to factory specs. Just IMHO a design error that they should have allowed in their firmware to offset like they do for calibrating the door reading to the actual reading. this is a change in their firmware that would cost nothing. and the heat piping well I am sure they have dealt with that by newer versions.
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