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F433921

Samsung RF18 Refrigerator Probem

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I recently have been experiences an issue with my Samsung RF18 where the both the refrigerator and freezer compartments defrost cycles are not working properly.  It will cool properly (Refrigerator 38 degrees F, Freezer -2 degrees) for about three week and the temperatures will gradually start creeping up in both compartments, eventually the refrigerator will not maintain 45 degrees and the freezer 32 degrees and both evaporator are a block of ice, circulating fans continue to run but no air circulation due to evaporator icing.

I have checked condenser and and found clean (no dust bunnies) and no air way restrictions.  I have also confirmed that the continuity of defrost heaters  elements and associated over temperature devices on both evaporators are within specifications.

The refrigerator and freezer evaporator defrost heaters are controlled by independent control circuits on the main circuit board.

I contacted my local appliance repair facilities and none are willing to service the refrigerator with it in the motorhome. One of them was nice enough to provide me with a copy the Samsung trouble shooting guide and the electrical schematics.  

I will run the diagnostic procedures tomorrow to see if determine why the evaporator defrost system are not working, I'm hoping that it maybe something as simple and a loose connection on the the wiring harnesses associated with the defrost circuits.

I installed the refrigerator about 4 years ago and has performs flawlessly unit this problem surfaced.

If anyone has had similar issues, I would appreciate if you would share your experiences.

Jim

 

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Jim,  I had mine repaired in the coach, however I had to pull the unit out of the recess and have it  where the tech could get to both the front and back of the unit. I had the part replaced and only had to pay for the labor. If I remember correctly the labor was about $300.00.

You might call Samsung (800-726-7864) and ask if there is a service center close to you that can do warranty work. (if your unit is under 5 years old)

Good Luck,

Herman

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Herman,

Thanks for the info.

Do you recall what the symptoms were when you were having your problem and what parts were replaces.?

 

Jim

 

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2 minutes ago, desertdeals69 said:

It might be the defrost timer.  Seen that before.

The defrost cycle is not a function of time like the old school refrigerator. 

The Samsung RF18 is a high tech unit that uses a micro processor to control the defrost cycles.  The refrigerator and freezer sections have separate evaporators and are controlled independently. Defrost cycles are only activated when icing is detected and duration of each cycle is variable. 

Since the evaporator icing is occurring on both the refrigerator and freezer evaporators, it's leading me to believe that the problem lies with in the micro processor. The only reboot option is to interrupt power to the unit. have tried this with no success. I have run the self diagnostics and no faults have been detected in the temperature sensors and the only component common to both the refrigerator and freezer defrost is the microprocessor.

Jim

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Jim's Response.

       The Samsung RF18 is a high tech unit that uses a micro processor to control the defrost cycles.  The refrigerator and freezer sections have separate evaporators and are controlled independently. Defrost cycles are only activated when icing is detected and duration of each cycle is variable. 

Jim, A number of microprocessor system's Do Not like the modified waveform generated by a number of the  inverters. There are a number of manufactures that state that fact in there technical information. Many others do not specify the information.  Modified waveform can mess up the clock and timing circuits.

Rich. 

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3 hours ago, F433921 said:

The defrost cycle is not a function of time like the old school refrigerator. 

The Samsung RF18 is a high tech unit that uses a micro processor to control the defrost cycles.  The refrigerator and freezer sections have separate evaporators and are controlled independently. Defrost cycles are only activated when icing is detected and duration of each cycle is variable. 

Since the evaporator icing is occurring on both the refrigerator and freezer evaporators, it's leading me to believe that the problem lies with in the micro processor. The only reboot option is to interrupt power to the unit. have tried this with no success. I have run the self diagnostics and no faults have been detected in the temperature sensors and the only component common to both the refrigerator and freezer defrost is the microprocessor.

Jim

I did not give a description of the timer mechanism.  What I was saying is if you monitor the current to the defroster heater, assuming they are ok, then you can tell where the problem is.  Measure the current and time to verify the circuit.

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1 hour ago, DickandLois said:

Jim's Response.

       The Samsung RF18 is a high tech unit that uses a micro processor to control the defrost cycles.  The refrigerator and freezer sections have separate evaporators and are controlled independently. Defrost cycles are only activated when icing is detected and duration of each cycle is variable. 

Jim, A number of microprocessor system's Do Not like the modified waveform generated by a number of the  inverters. There are a number of manufactures that state that fact in there technical information. Many others do not specify the information.  Modified waveform can mess up the clock and timing circuits.

Rich. 

Rich,

There many of the  Samsung RF18  in RV's that are running on modified sign wave inverters.  I contacted Samsung 4 years ago and was insures that the RF18 would perform without  problems with on modifies sign wave power sources.  The heaters are 120 v calrod heater the refrigerator heater 120 ohms (120 w) and freezer 60 ohms (240 watts).  Both heater check OK

The builtin diagnostics allow you initiate the IO outputs for the different functions by operating the touch pads that control temperature setting. I have no voltage at the heater junctions on either heater.  The processor output operated an ice cube relay  mounted on the circuit. My next check it determine if the relay is getting a signal from the processor and to determine if there is 120 v at relay contacts.

We keep you posted as I work my way thru it.

Jim

 

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7 hours ago, F433921 said:

Herman,

Thanks for the info.

Do you recall what the symptoms were when you were having your problem and what parts were replaces.?

 

Jim

 

Jim I looked but couldn't find my paperwork on my service call. 

Sorry. 

Herman 

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1 hour ago, hermanmullins said:

Jim I looked but couldn't find my paperwork on my service call. 

Sorry. 

Herman 

No problem,  I can't remember from day to day where I put anything.

Jim

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50 minutes ago, manholt said:

Jim, does that include DW & Coach?  Sorry, could not help myself. :rolleyes::P

Not quite that bad yet.

 

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Same refrigerator in my coach and the frig part defrost failed.  Using the Samsung schematics I was able to locate the defrost heater leads in the rear of the unit and found I had an open circuit.  Ended up being the thermal fuse located near the heating element.  Cheap part but a pain to replace.  I now carry a spare.

Contrary to what Samsung told you, I was tole NOT to run it on a modified sine invertor.  Guest it's all in who you talk to.  Regardless, I am using a pure sine and still blew the thermal fuse so maybe it really doesn't care.

Yours being both freezer and frig probably a different issue.

Lenp

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8 hours ago, lenp said:

Contrary to what Samsung told you, I was tole NOT to run it on a modified sine invertor. 

I called them when we were shopping for a refrigerator also. All I got was "it run on house current only" :wacko:. I made my way up their tech department and everyone was stumped. I gave up and bought a GE that I saw in a Fleetwood product at an RV show. GE told me Modified Sine wave inverter is fine as there are NO delicate electronics in that particular model. Its the computer circuits that usually will not run on MSW.

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I have an RF18 Samsung in my coach. put it in in 2012, have run on MSW every time that I move the bus from one location to another, have had zero problems so far.

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Kay, IMHO it's...luck of the draw!  Most Samsung's, like yours, then there is the other 5% !  It's across the board on practically anything! 

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On 12/2/2019 at 9:45 PM, F433921 said:

I recently have been experiences an issue with my Samsung RF18 where the both the refrigerator and freezer compartments defrost cycles are not working properly.  It will cool properly (Refrigerator 38 degrees F, Freezer -2 degrees) for about three week and the temperatures will gradually start creeping up in both compartments, eventually the refrigerator will not maintain 45 degrees and the freezer 32 degrees and both evaporator are a block of ice, circulating fans continue to run but no air circulation due to evaporator icing.

I have checked condenser and and found clean (no dust bunnies) and no air way restrictions.  I have also confirmed that the continuity of defrost heaters  elements and associated over temperature devices on both evaporators are within specifications.

The refrigerator and freezer evaporator defrost heaters are controlled by independent control circuits on the main circuit board.

I contacted my local appliance repair facilities and none are willing to service the refrigerator with it in the motorhome. One of them was nice enough to provide me with a copy the Samsung trouble shooting guide and the electrical schematics.  

I will run the diagnostic procedures tomorrow to see if determine why the evaporator defrost system are not working, I'm hoping that it maybe something as simple and a loose connection on the the wiring harnesses associated with the defrost circuits.

I installed the refrigerator about 4 years ago and has performs flawlessly unit this problem surfaced.

If anyone has had similar issues, I would appreciate if you would share your experiences.

Jiim

UPDATE

Ran diagnostic of microprocessor today, all test were performed thru at least 2 cycles. Test were performed with refrigerator on both shore power and invert.  

Refrigerator had been running for 40 hours prior to first test,  freezer temperature -4, refrigerator 38 at beginning of test.

No fault codes were found. Guess this was no surprise because both freezer and refrigerator have operated normal since the evaporators were defrosted by disconnecting the power cord .

There is a disclaimer in the diagnostic procedure instructions that the diagnostic only check input sensor and process outputs.

Diagnostics doesn't confirm the 120V components such as defrost heaters, fans ans compressor are functional.

I have confirmed the all heaters, compressor, fans and external protective device (thermal devices, fuses)  are functional.

The only item left to check is the connection on the PCB that power  the defrost.heaters.  If this checks out OK, I will just wait until it fails again and run the diagnostic  when in a fault condition.

Unfortunately there  no CHECK ENGINE  light that set the codes.

 

Jim

 

 

 

 

 

 

 

 

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2 minutes ago, huffypuff said:

I still have a fine working Norcold going on 14 years old.  😂

 

3 minutes ago, huffypuff said:

I still have a fine working Norcold going on 14 years old.  😂

I had one of them too, but after 5 failures of the retro fit  and reading stories of motorhomes with the  retro fit still going up in flames I decided to make the change. When I removed my Dometic there was a section of charred wood  adjacent to the stack.  My brother-in -law is one of those whole lost his MH from a refrigerator fire,

Jim

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Jim, my Whirlpool gold runs on zero -1, freezer and +37 fridge.  I would think zero -4, on freezer is a tad to cold, since your in Washington State.  Do you keep your coach in a garage or outside?

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56 minutes ago, huffypuff said:

I still have a fine working Norcold going on 14 years old.  😂

Mine did to right up to where it quit on a trip and left me living out of a ice chest. 

Bill

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1 hour ago, manholt said:

Jim, my Whirlpool gold runs on zero -1, freezer and +37 fridge.  I would think zero -4, on freezer is a tad to cold, since your in Washington State.  Do you keep your coach in a garage or outside?

The recommended temperatures in the owners manual are -4 and 38, that's what I have been using to date. I'm going to move it up to 0 to  see it helps.

I do store my rig in a 40' x 60' stick built shop and I've never seen it freeze inside. 

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