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Samsung RB1944SL refrigerator not coming out of defrost

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Trying to fix this Samsung RB1944SL refrigerator. Currently have to reset fridge every 6 hours to keep it working. Initially checked thermal fuses and defrost sensors and found freezer thermal fuse blown. Replaced both thermal fuses and defrost sensors per Samsung's service bulletin. Replaced original thermal fuses with bimetals per service bulletin. Did ohm tests on all sensors outside of fridge, and they seem to be fine, but problem continues. Tried new main board without success. Manual suggest checking voltage at the main board after a forced defrost. Put fridge into forced defrost, but not sure how to test voltage at the main board. Also found short in wire that runs down the fridge door to the front display.(What engineer thought running wires through a hinge would be a good idea?)  Any way to get into the door to replace that wire bundle? Any help would be appreciated as this fridge is driving me to drink, and it will have to be warm beer.

 

 

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Are you certain it gets stuck only when coming out of defrost or does it just shut down after a cooling cycle or intermittently?

ps... you indicated the manual suggests testing at the board. but you subsequently requested a manual. It's no big deal, just confused and you'd be surprised how seemingly innocuous things like this may help us in solving your problem.

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Thanks for the manual post. Just wondering whether there was a different manual  for the 1944  So yes as best as I could tell, it was fine until it went into the first defrost cycle. I opened the freezer and fridge backs and put it into forced defrost and found that the drain pan in the freezer was not heating. (The freezer defroster seemed to heat, as did the fridge defroster coil and drip tray.) So I replaced the drain pan and all was well for about a week and once again it spontaneously thawed and warmed (freezer and fridge) I went back and checked and everything seems to still work in forced defrost, and the compressor runs in forced compressor. I am now officially stumped.

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Any ideas?  Samsung guys? Ohm?

Sadly, I am afraid this fridge will soon head to the scrap heap

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.. May be a losing cause but we got your back and we aint gonna let you go down by yourself and without a fight. gimme a bit... gonna get some coffee and check out the manual. Hopefully I may find a suggestion or two

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... Replaced both thermal fuses and defrost sensors per Samsung's service bulletin.

part numbers of the

Defrost Fridge Sensor   ?

and the

Defrost Freezer Sensor   ?

 

Which Samsung Service Bulletin number ?

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and the Sensors are all in correct location, physically ?

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Have you used the self diagnostics?

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This is Samsung service tip with part #'s for this unit hope it makes it easier

 

 

Service Tip (Local)

  Close  

Refrigerator Stops Running Until Unplugged Category Home Appliances > Refrigerator > Bottom Freezer Model Code RB1844SL/XAA / RB1844SW/XAA / RB1855SL/XAA / RB1855SW/XAA / RB1855VQ/XAA / RB1944SL/XAA / RB1955SH/XAA / RB1955SW/XAA / RB1955VQ/XAA / RB2044SL/XAA / RB2044SW/XAA / RB2055BB/XAA / RB2055SL/XAA / RB2055SW/XAA / RB2155SH/XAA / RB2155SW/XAA Added by STEVEP Registered date 06.01.2008 Description

 

 Symptom: Refrigerator stops running and cooling daily and will not run unless unit is unplugged and plugged back in.

Models Effected:RB units with  4 letter model numbers such as RB2055 / RB1944 / RB1844  etc .......

Possible Cause and Diagnostic Procedure.

  • Check Both Defrost Circuits for Open Thermal Fuse.
  • Access Main PCB in compressor compartment and locate CN70 connector.
  • For Refrigerator compartment check for an open circuit by taking a resistance reading between WHITE and GREY / For Freezer side check between BROWN and GREY.
  • If open Thermal Fuse is identified it is recommended to replace both compartment Thermal Fuses with a Bi-Metal  as well as both Defrost Sensors.  
  • Bi-Metal # DA47-10160H
  • Sensor #DA32-00006W               

Read more: http://appliantology.org/topic/40783-samsung-refrigerator-rb2155sh-xaa-shuts-down-every-6-hours/#ixzz2WRIPEzb2

 

Defrost sensors are both in bottom left corner. Bimetals are both tucked along the left side of the evap coils. Self diagnostics never showed an error code even when the drain pan didn't work, as I suspect as long as the coil defroster worked, although the defrost circuit didn't show the right voltage drawm since it seems that the pan heater and the coil heaters are in series, it never kicked an error code.

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okay, so the thermal fuses are normally closed. Then after defrost they open, signaling the board to terminate defrost? if this is true, and you replaced the board, sensors and fuses, maybe check the defrost circuit when the fuses should be open. Ie manually defrost fridge and then check circuit to see if it is open. If still closed, subject to faulty new parts or improper installation, i would check for a short in the defrost circuit which would fool the board into thinking the bimetal never opened. This scenario would also explain why there is no error code in the diagnostics .... it is testing for normally closed fuses and not checking to see if they open. Just a theory to check out, I aint no Samsung expert and Lord knows I aint no electrical whiz kid.

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i would check for a short in the defrost circuit which would fool the board into thinking the bimetal never opened. 

 

This tactic has a lot of merit especially since a damaged wire harness and one short have already been identified:

 

 Also found short in wire that runs down the fridge door to the front display

 

If there is another wire harness short, it may not be a constant short but instead could be dependent on the position of the door, ambient temperature, etc. Could be very hard to catch.  

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Also make sure to run diagnostics prior to unplugging fridge. Removing power will erase defrost codes on Samsung fridges for 4-6 hours

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So as best as I can tell, the bimetals function only as overheat fuses and don't signal the board to end defrost. The voltage through the defrost sensors should shut down defrost when they reach a set temp. I tried the diagnostics prior to resetting the fridge and no codes showed. Interesting, last night when the freezer started to warm, I tried unplugging to reset and the fridge started to cool, but the freezer continued to try to defrost?!? I think this thing is possessed. I haven't changed the board, but the current board does not show any obvious issues (burned transistor, break in printed circuit etc.)

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 I haven't changed the board, 

 

But you already changed this previously, right?...

 

Tried new main board without success.

 

It is possible that the new board is bad.  Also possible that there's been a modification to the board (algorithm, reduced sensitivity to RF, etc.) but you're getting one of the old batches.  Without access to Samsung's proprietary servicer site, GSPN, there's no way to check for recent service bulletins.  Difficult access to service information is one of the big reasons I do not recommend the Samsung brand in my appliance brand recommendation report.

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This tactic has a lot of merit especially since a damaged wire harness and one short have already been identified:

 

 

If there is another wire harness short, it may not be a constant short but instead could be dependent on the position of the door, ambient temperature, etc. Could be very hard to catch.  

 

Short could be acting up from amperage draw during defrost.  Can provide resistance values for sensors if needed.

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So as best as I can tell, the bimetals function only as overheat fuses and don't signal the board to end defrost.

Based on the service bulletin, replacing thermal fuses is the first suggestion to solve fridge not coming out of defrost problem. If it does not act as a terminator then a bad fuse must somehow interfere with the termination process.

Also based on your latest info... if a short is not found it sounds like you need a new (another?) board.

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