FIXED Samsung RFG298AARS/XAA Fridge section is fine, freezer does not freeze

[Bob_Dittmar]

Model Number

RFG298AARS/XAA

Brand

Samsung

Age

More than 10 years

Hello

Apologies if this has been covered on this forum already, but I could not find my model number and this topic although I found this topic for other models. I reviewed those threads but still have some questions.

Symptoms:

• Refridge section can reach 34F no problem.
• Freezer section doesn’t have any cooling – even when put the front panel in Power Freeze mode.

I replaced the freezer compartment temp sensor DA32-10105B as that was quick and easy to order, and this was before I learned how to read the current temp from the front panel… No change in behavior after changing this.


I’ve now been using Samsung publication tsRFG298AA rev 03/30/2011 for troubleshooting and mainboard diagrams.

Run the self-diagnostic, no LED error codes show on completion.

• Forced an error by disconnecting some sensors and diagnostics detected it with LED code, so diagnostic routine runs.

With freezer door switch closed, I can feel the air from evaporator fans moving through the back panel duct work. So Fans are working and controllable by the controller.

Pull the back panel of freezer compartment to expose the evap coil, leave the fan assembly plugged in so no sensor errors and close the freezer door switch.

• Evap coil never cools or frosts, only slightly cool to the touch but this might be conduction from the refridge maybe???

Compressor is running and the fan for condenser coils is running.
I put the compressor into Force Mode and checked all 3 speeds – by hearing increased rate, not measuring voltages.

Have monitored temp sensor voltages at CN30 to the mainboard ground and show the closest conversion to temp using the table in the troubleshooting guide.

• Cn30-3 F Sensor: 2.016v (62.6F)
• CN30-4 F defrost sensor: 2.158v (57.2F)
• CN30-6 R sensor: 2.781v (35.6F)
• CN30-8 R defrost sensor: 3.630v (3.2F)

Reseated all connectors on the mainboard and the power inverter board.
Reseated connector on the stepper valve.


Some other things I’ve noticed:

• Once after probing on the mainboard connectors and reseating connectors by the evap coil assy, the evap coil did start to chill and form some frost just near the entry of it. But then after unplugging the unit to button some things up, it never chilled the evap coil anymore. I cannot attribute what I might have done to allow the Freon to get to the evap core.
• When cycling power, sometimes the inverter board doesn’t start up properly.
  • Several times it gives no LED status.
  • Several times I get single pulses for startup failure.
  • Several times I get dual pulse for SPM fault.

My suspicions are:

• Mainboard is going into defrost mode for the freezer but is never coming out of it.
  • The defrost sensor seems good, so not sure what else can cause this.
• Stepper valve is not working to engage the Freon to the freezer evap.
  • Not sure how to test/verify this.
• If nothing else makes sense, then maybe bad main board?

Suggestions would be appreciated.
Bob

 

[rickgburton]

Compressor is running

The problem is either the 3-way valve or it's in the sealed system. Your machine uses a three way valve to distribute the refrigerant to either the freezer evaporator or the or the fresh food evaporator or both, depending on the model. If you have the tech sheet it should tell you the resistance of the valve coils. I have no information for that particular model. There could also be a refrigerant leak or a cap tube restriction. You're probably going to need someone with a get of refrigeration gauges.

 

[Bob_Dittmar]

Hi Rick
Thanks for your time and reply.

I also suspected the stepper valve (3-way valve) as it seems the fridge side worked but maybe the freezer side of it wasn’t . The tech sheet I have doesn’t list the coil resistances, but I can ohm out each coil and see if they are identical.
Also though about some blockage in the closed system such as the freezer expansion valve, or whatever this system uses for the gas expansion. As you suggest, I’d need to have it looked at with gauges.

As I mentioned in the original post, one time when I was fiddling with the freezer’s sensors and fan connectors, the valve did kick in and allow the evap coil to cool, so if it is a stepper valve problem, it is intermittent not a hard fail which I think is unlikely given some more steps and behaviors I see that I describe below.

I thought about what I was doing when the one time the evap coil did cool and I tried something to try to replicate it. here are the steps and observation:

• With the system running
• I unplugged the freezer temp sensor
• the system turned off the evap fans which is expected.
• Plugged back in the sensor
• evap fans started back up.
• Then the freezer started to cool and was able to get down to the setting I had of -2F

It’s as if this acted as a resetting of the control algorithm, as if the control loop was stuck in some waiting state and this allowed it to restart or get past whatever condition was holding the control loop.
Freezer reached the -2F setting and held it for some time....

But several hours later:

• I see the front display flashing “-2” on the freezer LED, nothing shown on the fridge LED.
• When I press either the freezer or fridge buttons which normally show the temp settings and the realtime temps, there is no response.
  • The display stays flashing “-2” on the freezer LED.
• Power inverter PCB red led is solid on, not flashing any diagnostic strobe.
• And the freezer compartment is no longer cold.

So something affected the operation after it had been running. And from the system not having any response to any of the buttons, it seemed the controller/processor is in a locked up state.

After power cycling several times to get a steady power inverter PCB led status, the fridge compartment cools down, but the freezer doesn’t.

Once again, I unplug and replug the freezer temp sensor while system is running and then the freezer starts to cool down and can reach the temperature setting.

It has reached it’s new setting of -4F and held steady for about 5 hours as of this reply.

After these steps and observations

• I don’t suspect the stepper valve any more as it can be activated by the controller.
• I don’t suspect something in the sealed system since it seems to be able to reach both the fridge and freezer set temperatures.

I’m leaning more that it is electrical component and possibly the mainboard since:

• The power pcb not coming up in a running state on every power cycle can be caused by an issue with the control CN75 signals from mainboard.
  • It doesn’t always come up in the same error state, some times it is single led flash, sometimes it is two flashes, sometimes it is three flashes.
  • I think if the problem was with power inverter PCB, then it would come up in the same failed state - just my guess though.
• The mainboard’s freezer control loop/algorithm seems to stop, but giving it some sensor reset by unplugging the freezer temp sensor seems to start the control loop.
• The front door panel display/buttons had completely locked up and non-responsive that one time.
  • This could happen if the mainboard processor stopped running.

From your experience, how often do these controller boards fail?
From the above steps and behaviors above, would you consider it a controller board issue or something else I can check?


Regards,
Bob

 

[Bob_Dittmar]

After running properly for about 10 hours with the freezer holding -4F, the same behavior occurred again:

• Freezer LED flashing -4
• Freezer not chilled any more
• This time the front buttons do respond to being pushed and I can run diagnostics which show no failure codes.
  • I thought the first time this happened the buttons had no response and mainboard was not responding, but it was late at night and maybe I didn’t try enough of them – the mainboard may not have been locked up like I thought…

I can’t find anything in documentation about what causes the temp setting to flash on and off on the front panel LED. Need to try to find this out.

 

[rickgburton]

Sounds like it could be the main board.

how often do these controller boards fail?

Very often!

 

[Bob_Dittmar]

Thanks Rick,

It’s not too expensive to buy and replace myself – I’m gonna give that a shot at this point.

Will update this thread after I've done this swap out for the benefit of others.

Bob

 

[rickgburton]

OK sounds good keep us posted

 

[Bob_Dittmar]

Ended up being low Freon after all…

The upper fridge unit was able to cool to what appeared normal but lower freezer unit wouldn’t, which lead me to believe the control board wasn’t sensing and engaging the 3-way valve properly. But seems the amount of Freon was enough to chill the fridge but not the freezer.

I really didn’t want to “mess with” the closed system since there are no service points installed. After catching some youtube videos, I picked up a BPV service kit and installed on the low-side stub line.

The low side was in the negative, added R134a until it was to 1 to 2 psi.

System is back to running fine, but there obviously is some slow leak somewhere.

Might just be easier to see how often I need to add Freon.

 

[Jake]

Rick hasn't been here since last Wednesday, he is under the weather.

But yes, sounds like a leak, so if you are not able to locate the leak keep adding Freon when needed.

Jake

 

[rickgburton]

Might just be easier to see how often I need to add Freon.

That would be the easiest. If it's a small leak add some dye the next time you add gas.