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KRSF505ESS00: RC gets cold/warm inconsistently while FC is working fine.

v8power

Premium Member
Joined
Dec 27, 2017
Messages
19
Location
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Model Number
KRSF505ESS0
Brand
KitchenAid
Age
1-5 years
The refrigerator compartment sometimes stays around the set temp and sometimes warms up for extended periods. This has happened over the past 6 months with it getting warm more frequently and warmer in temp as time went on. Even to this day, the temp sometimes gets to normal, but then it later warms, again. The freezer has been working well.

I checked all thermistors. They showed proper resistance for the given temperature.

The RC evaporator was NOT iced up. The RC fan works just fine.

RC drain was clogged with rust with no water going down, but I cleared this, and I'm still seeing the RC take a while to cool and then even get warm, again.

Sometimes I'll exit diagnostic mode or restore power to the unit and see something strange: the FC is immediately cooled, but the RC may not be cooled at all for a long while (perhaps a half hour or more) even if it's 50 degrees F inside. I'll see the FC cooled at lower compressor speed until finally the unit decides to cool the RC (and then the compressor may run at high speed). I've also seen it alternate cooling FC and RC at lower compressor speed, and the RC finally reached the set temp after a number of cycles.

Does this information point to an obvious problem, or is more investigation necessary?

Thank you!
 

v8power

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Dec 27, 2017
Messages
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Location
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Was there any frost at all on the evaporator?
No - no frost seen - unless I ran it without the fan.

In less than 12 hours, I see my RC performance improved dramatically after cleaning the condenser coils - I'd say it's working perfectly so far. I used a shop-vac to blow some dust out as it seems impossible to reach in there. Any other recommendations for cleaning?

Thank you.
 

rickgburton

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v8power

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Messages
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Thank you for that brush.

It seems I declared victory too soon. I put everything back together and freezer is still good, but fridge is in the range of 40-45 degrees F (target setting is 34 degrees). What is confusing to me is that it stayed at 70 degrees for hours before it even attempted to cool the fridge side (and initially stopped at 52 degrees). Is that normal?
 

rickgburton

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no frost seen
It sounds like you may have a problem with the sealed system. Your machine uses a 3-way valve that directs refrigerant flow either to the freezer evaporator or the freezer and refrigerator evaporator at the same time. If there's no frost on the evaporator, the evaporator is starving. It could be a refrigerant leak or a partial restriction in the cap tube or a problem with the 3-way valve. Unplug the machine for several minutes. Put your hand around the 3-way valve and plug he machine back in. If you feel the valve move to the home position the valve is probably good. Check your warranty. I believe that machine has a 5 year warranty on the sealed system.
 

v8power

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Messages
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If there's no frost on the evaporator....
Sorry - regarding frost, I meant I didn't see any residual frost when I first looked at the evaporator and everything was off. With everything apart, the fan removed, and turned on, I saw the RC evaporator frost up uniformly.

I moved my wireless thermometer from the bottom door bin next to the cabinet thermistor, and it's suddenly reading 5 degrees colder, so perhaps things are working a bit better than I thought a couple hours ago.

Could my issue with the fridge be one of expectations? Yesterday, I turned on cooling after it being off for 2 hours. The interior temp of the fridge was 70 degrees. It took hours before the RC evap fan ran or run the compressor ran full speed. When I finally heard the compressor ramp up, the RC fan turned on a minute later, and the fridge cooled down to 52 degrees F (as measured by the bottom bin of the door). Then, the compressor ramped down and the RC evap fan turned off. I would have expected the fridge to start cooling immediately since it was so warm initially. Am I being unreasonable in my expectations?
 

rickgburton

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OK, make sure the evaporator cover is installed. After 24 hours with few door openings, leave the machine plugged in and running and remove the evaporator cover and check the frost pattern. See if you can locate your tech sheet.
Tech Sheet Locations.jpg
 

rickgburton

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v8power

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Messages
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Location
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I took the cover off and took a picture of the RC Evap when I detected the RC start to cool. I believe the frost pattern indicates a problem (see pic). Would you agree? Thank you.

RC_Evap.jpg
 

rickgburton

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Is there a foam gasket between the cover and the evap compartment? Look at the gasket.
 

v8power

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Messages
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Location
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It is possible I introduced an air leak, recently, as it's difficult to get the foam gasket around the metal flange on the right. This most likely didn't cause my initial complaint of poor performance, though, as I only just took it apart to start this investigation - it may have been fine from the factory.

Machine seems to be working well now that we're not opening it as frequently (most fresh food moved to other fridge). I set fridge temp to 34 degrees, and wireless thermometer situated next to thermistor reads cycles of 34-39 degrees consistently.

I'm still wondering why a much warmer RC cabinet - like over 50 degrees - can take hours to cool down (once I finally hear the compressor ramp up to max speed, then the temp starts to fall).

Thank you.
 

rickgburton

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I'm still wondering why a much warmer RC cabinet - like over 50 degrees - can take hours to cool down
As much as 24 hours. It's in the design of the machine so as not to over tax the compressor.
 

v8power

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Messages
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Location
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As much as 24 hours. It's in the design of the machine so as not to over tax the compressor.
So, either we were recently abusing the fridge (opening door too much, putting in warm food, etc), or there is an efficiency issue. I did just address plugged drain (and I notice the humidity levels are now 10-15 percentage points lower). Would that have a major contribution to efficiency? If not, what else should I check?

Thank you!
 

v8power

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Messages
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Location
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The fan seems to be on during intended RC cooling, but I don't know of a way to be certain the machine is asking for the RC side to cool during normal operation. In diagnostic mode, both fans reacted correctly 100% of the times I tried turning them on/off during the fan test. When I ran the compressor diagnostic test, the fans reacted correctly.
 
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