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dalbert

Samsung RM255LASH/XAA - Compressor works, no air flow and no cooling inside fridge/freezer

52 posts in this topic

A few questions:

  1. Is servicemanuals.net any good? They have a manual for this fridge, but their "sample" has nothing within it which would indicate the quality of the full document.
  2. Is there a test mode for Samsung fridges, akin to what I've seen on an LG model in this video?
  3. What might cause all the fans in the freezer/fridge compartments to not blow?
    1. How can I test them? Either the sensors or the fans themselves.

 

My compressors runs, judging by the noise. The fan between the compressor and the coils is spinning, blowing fairly hard.

There is no airflow from any of the vents in the fridge/freezer. We first noticed the problem in the freezer, and as of right now the freezer is 56 degrees and the fridge is holding steady at 38 despite being in Power Cool mode.

 

I'm wondering if there is some single point of failure that would cause all 4 fans to not run. The easiest thing would be to replace the motherboard, but how can I verify that this is the real problem? I've found on the circuit diagram a connector with labels for various fans. I disconnected it and tested the voltage between the ground pin and each of the others, both on the plug and the receptacle, and got noting for any of the pairs. I was pretty sure that when I pulled the connector some of the humming stopped, like I'd perhaps killed a single functional fan. I just tried that again, and it's definitely stopping something (not the compressor) when I unplug it. It sounds like it's coming from the lower fridge compartment, and indeed there are pop cans in there that are still quite cold. Seems strange that 3 out of 4 would go bad together. 

 

See my motherboard here.

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Samsungs typically have a magnet switch that has to be closed before the fans will come on. So with the door open you may have to run a magnet around the top until you find it. Then verify that you really don't have airflow. You may not feel airflow if your evaporator coils are iced over as well. Is this a newer model? I've only worked on 2 of these with the 4 sections and they were probably around 2008. I had thought these were discontinued. They are a bit of a pain. One wasn't holding correct temp in the bottom left drawer. Changed a board on that one. Another had an iced over coil in the freezer section and bottom drawer. I believe we changed the defrost thermistor. I would get the manual from this site. I think that servicemanual website you linked is probably not a trustworthy source. I cannot zoom in on your pic for some reason to read the board connectors. Typically your fans run off of dc and you would test the connectors with needle point leads to verify voltage.

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Yes it is from that time, around 2008. 

Here's a plain, high resolution photo. 

 

I've found no ice anywhere, and I cleaned out all dust/cat hair from the compressor/coil compartment. Are there multiple coils throughout the unit? I assumed there was just the one, next to the compressor, with the manilla-colored fan between them. Here's a pic of the bottom-back of the fridge to show what I'm talking about. I just checked the air flow like you said. Turns out you just need to hold down the switches that keep the lights off when the doors are closed. I checked all 4 compartments and all 4 have air flow. So,

  • I've found no ice
  • I have air flow
  • the fan next to the compressor is spinning
  • the compressor is hot but not skin-burning hot
  • the freezer compartments are warm (50s)
  • the fridge compartments are cold, but warmer than their settings (set to low 30s, actual temp is 38)

Should I unplug the unit for a while to allow any unseen ice to melt? Is it even possible that there is unseen ice, or have I seen pretty much everything already just by looking behind the 2 removable panels on the back of the unit?

 

About the manual: from my searches around this site I'm not sure if the service manual is here. There's a fast track manual for RM255, but I'm not sure what that is. And there are service bulletins. I see here that someone PM'd the manual to someone else, maybe I can get the same treatment after I subscribe.

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I believe you do have to subscribe and then you can request a service manual in the forum labeled service manual request. If the fans are blowing and compressor is running it could be a sealed system issue. You would need to pull the covers inside to see what your frost pattern looks like.

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the fast track is what you need. You need to run diagnostics and that info is found in the fast track. It's possible you have a sealed system failure but check the fast track for thermistor testing info, as a failed thermistor can cause wacky things in a Samsung

Bryan, the four section Samsung fridges are alive and well but found in RF models. Although most models have 2 drawers, they are still designated as four door fridges. The RF32FMQDBSR, however, is a current 4 door fridge that looks similar to the model in question.

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Ah. I thought they were coming back but I still have a very strong dislike for them :)

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Some 4 door models have 2 compressors. One runs r134a. One runs r600a. R600a system you can service. Refrigerant lines are painted red.

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When you say "sealed system" are you referring to the refrigerant circuit, the stuff that only a licensed person can touch? Like a leak?

Can I trust that if the temperatures on the display are correct then the sensors are also accurate, ie that there aren't separate sensors for the display readout?

Additional evidence that the temp sensors are fine is the fact that when I hold the door-close-switch down the evap fans do come on, so it must know that the compartment is too warm.

 

I bought the subscription, got the fast track, pulled the back panel out of the freezer compartment. No ice, not even any condensation. That compartment is up to 63 degrees now - I figure if it had been iced over this morning then it would have stayed that way since I've kept it powered all day. That's what I experienced in the past when an air conditioner got frozen pipes.

I did not disassemble the refrigerator side b/c it's still full of food and I assume that finding no ice on the freezer side means it's not an icing issue. To verify my assumption: is it possible that ice on the evaporator coil on the refrigerator side could cause the freezer side to not work at all while still somehow allowing the fridge side to stay somewhat cool?

 

I did the self diagnostic. The first time the only error was one that the fast track says is to be ignored (Uart communication). I did it a second time after some disassembly and got additional errors but they all had to do with the fans, which were no longer attached. I checked voltage on the 2 defrost wire pairs by sticking probes into the back of the connector (touching the metal that's crimped onto the wire. I got 130vac on each. Plus I've seen no ice so this check was probably irrelevant.

 

Do I need to start trying to test all the sensors with a multimeter, or have I effectively ruled everything out and therefor must call a repairman to check the sealed system?

 

Also, thanks for these prompt replies. Though I haven't fixed anything, I've already learned a bunch today and I'd say this was $12 well spent.

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Bryan, I'm rignt there with ya, my brutha! Just wait 'til the fridges with sealed system cooled Samsung icemakers hit the market. I thought they decided to scrap that design but I understand they are on the way. Not as bad as the Frigidaire finger evap but a refrigerant line will run under and attach itself to the icemaker.

Edited by DurhamAppliance

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Regarding thermistors, no you cannot make that assumption. There are no short cuts when it comes to testing thermistors. Samsung specifically advises that thermistors should be tested at operating temps.

Regarding sealed system failure, yes that would require someone with knowledge and specialized license to repair. I don't see many Samsung sealed system failures, however.

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Bryan, I'm rignt there with ya, my brutha! Just wait 'til the fridges with sealed system cooled Samsumg icemakers hit the market. I thought they decided to scrap that design but I understand they are on the way. Not as bad as the Frigidaire finger evap but a refrigerant line will fun under and attach itself to the icemaker.

They are on the market now my brotha. They actually seem easy as long as you follow the steps. If you skip the forced defrost though, you will be buying the customer a new refrigerator.

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yeah, i remember disassembling one last year, that backwards arm upside down maneuver needs a bit of practice.

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I would concentrate on thermistors before changing the board. Samsung board failures are quite rare however you may want to check for voltage from the board to the 3 way valve as well as test the 3 way valve itself. Procedures should be in the fast track.

Edited by DurhamAppliance

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Still an unfinished product, Checked it yesterday and it yielded no results. I expect some good things from the site in the near future.

Edited by DurhamAppliance

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I got it at ASTI also the manuals and fast track should be available even to non warranty sometime in summer through Plus One

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Plus One has training videos as well but we will have the manuals and updated fast tracks in the download section in the next couple of days. Last year they gave out the manuals on a cd. This year, the trainer would put it on your data key if you asked. Of course, our folks asked.

The Sara site will only provide info advising the most common parts needed to repair a particular issue. It's about 75 to 85 percent accurate at the moment.

Edited by DurhamAppliance

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btw, you can take out the evap, ff and freezer thermistors and test them at 32f by submerging them in an ice water slurry (mostly ice) ... this will create the reference temp of 32f which you can compare with the chart in the fast track. You should get 13.29 k ohms +-5 percent. Since thermistors are cheap, it's only logical to rule them out first, even if it's not readily apparent that your problems are caused by one or more of them.

Edited by DurhamAppliance

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In about a month they will have a diagnostic tool that hooks to a windows computer to test samsung refrigerators. Nick said you can toggle defrost, run fans. All kinds of stuff. It will be available to non authorized servicers.

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I would concentrate on thermistors before changing the board. Samsung board failures are quite rare however you may want to check for voltage from the board to the 3 way valve as well as test the 3 way valve itself. Procedures should be in the fast track.

I'm not seeing anything about a 3-way valve in the fast track or the bigger Samsung PDFs. Are you referring to the device that switches the compressor between 2 different modes? I can't remember how to describe it, but at some point during yesterday's googling I read something about the thing in this photo, circled in red.Is that what you're talking about?

 

I checked the voltages of all the wire pairs for which a target voltage was given in the fast track on the "CN30" connector. They all seem reasonable given the temps that I think are in the compartments (I don't have a temp probe to precisely measure the real temps). I haven't checked resistances, I guess I'll do that next.

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that's it. on page 1 of the fast track you see it in the drawing listed as "3 way valve."

CN 75 on the board controls it.... how do we know since the board markup on page 4 doesn't refer to cn75 as the valve connector? Look at the schematics on page 9. There you see it, but this time it is called a stepper motor valve and it is called out at CN 75. Easy Peasy... lol.. yeah right.

Edited by DurhamAppliance

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I see, thanks for the clarification. Ok, so CN75 - Checking voltage between the black pin and all the others I get nothing. I tried both by probing the back of the connector and by removing the connector and touching the pins sticking out of the board. I also tried checking the resistance while the connector was off, and got nothing. Stayed at a solid 1 for all of them.

If I use the black wire in CN78 as my ground, then I get 13.5 vdc on every one of CN75's pins (connector attached, not sure if that matters).

 

I don't actually know what I'm supposed to be doing, I just figured I'd start by getting all the voltages. This should mean that the 3-way diverter valve is getting power, right?

Now how do I test the diverter itself?

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Check the voltage of the evap thermistors and then find the corresponding temp on the temp chart. Then turn on power cool and power freeze and see if the temp lowers on the evap. (Monitor voltages at thermistors.) if your temp lowers on the evaporator your diverter is good. Turning on power cool and power freeze flows refrigerant to both compartments.

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Pins 2-3 is a coil and should show some continuity.  The same with 4-5.  Voltage is on pin 1. From your test,  it appears the coils are okay. (voltage passing through them from line 1 shows continuity among the coils ).  Now we need to determine if voltage is sent to move the valve.... Applianceman provided the procedure and you can find it on pages 6 and 7 here:  http://appliantology.org/files/file/1335-samsung-refrigerator-technical-training/

Edited by DurhamAppliance

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