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FIXED KRFC704FBS01 Cold Freezer, but the top of the fridge is warm when the bottom is cold.

Yang

Premium Member
Joined
Apr 21, 2022
Messages
4
Location
Rhode Island
Model Number
KRFC704FBS01
Brand
KitchenAid
Age
1-5 years
Hello,

My refrigerator is warm on the top of the fridge while the freezer works well. I notice there is a thermistor in the pantry drawer at the bottom of the fridge (it is cold there) and it shows the exact temperature there when I run the diagnose mode.

But the evaporator fan doesn't run to circle the warm air at the top of the fridge.

I did research and read the forum trying to find the solution to solve the problems of my refrigerator.
I think this one is very similar:

but i have different data as show below.

Service Test 01 RC Thermistor = 43
Service Test 02 FC Thermistor = -13
Service Test 03 RC Evaporator Thermistor = 77
Service Test 04 First FC Evaporator Thermistor = -18.4
Service Test 05 Pantry Thermistor = 34

Pin Voltages:
P8. P8-1 to P8-2 (5VDC) RC EVAP THERMISTOR OUTPUT = 1.5 - 5VDC (MAXIMUM) This reads 4.98V
P8. P8-3 to P8-4 (5VDC) FC EVAP OUT THERMISTOR OUTPUT = 1.5 - 5VDC (MAXIMUM) This reads 4.98V

P14. P14-1 to P14-2 (12.7VDC) FC EVAP FAN OUTPUT This reads 12.6 volts when fan is on
P14. P14-3 to P14-4 (12.7VDC) RC EVAP FAN OUTPUT This reads 12.6 volts when fan is on

P5. P5-1 to P5-2 (5VDC) FC THERMISTOR OUTPUT = 1.5 - 5VDC (MAXIMUM) This reads 4.98V
P5. P5-3 to P5-4 (5VDC) RC THERMISTOR OUTPUT = 1.5 - 5VDC (MAXIMUM) This reads 4.98V

I removed the cover to see the evaporator in the fridge and found the ice built up at the top. (I defrosted it manually two days ago)

20220422160203.jpg


Any ideas about what I should do for the next step?

thanks! looking forward to seeing your replies.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
130,312
Location
Redmond, Oregon
Like I mentioned in post #2 of that other thread the thermistor seems to be the problem, you said on yours--->Service Test 03 RC Evaporator Thermistor = 77

77 degrees F on the evap. thermistor? Did you take a real time temperature of the evap. thermistor as well?

RC EVAP FAN OUTPUT This reads 12.6 volts when fan is on
So you are getting the proper voltage to your RC evaporator fan motor. So your control board is good.

So I'd order the same exact part and should fix it like it fixed his in that other thread.

You can only get the RC thermistor only when you order the complete RC evaporator fan motor and cover assembly W11395558:

Jake
 

Yang

Premium Member
Joined
Apr 21, 2022
Messages
4
Location
Rhode Island
Thanks for your reply. Appreciated.

I didn't take the real temperature on the evaporator thermistor when the service test shows 77F. But i removed the evaporator cover quickly after the test, the evaporator thermistor has been covered with the ice at that time as shown in the picture above. It should be around 32F instead of 77F, even though i didn't take the real temperature.

Besides, do you have the thermistor resistance chart for reference?
I did test the resistance of RC thermistor and RC evaporator thermistor under room temperature(around 65F). One shows around 3k+Ω and another one 1K+Ω. I forgot the exact number. But they varies a lot.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
130,312
Location
Redmond, Oregon
do you have the thermistor resistance chart for reference?
This should be it here:

Jake
 

Yang

Premium Member
Joined
Apr 21, 2022
Messages
4
Location
Rhode Island
Thanks, Jake. This is very helpful and it narrows the causes of the issue down to the evaporator thermistor. When I test the resistance of the eva. thermistor under RT and it only shows 1.3KΩ which is absolutely wrong (the correct value should be around 3.6KΩ). I found a good thermistor by chance and replaced it by cutting the wires (trying to give it a shot before ordering the whole assembly). Then it works perfectly now and no ice build-up on the evaporator either.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
130,312
Location
Redmond, Oregon
Sounds good Yang.(y)

Let us know if it keeps working good with the thermistor you replaced only, if so please post the part number of it so others will know too.

Jake
 

Yang

Premium Member
Joined
Apr 21, 2022
Messages
4
Location
Rhode Island
Hi Jake,
it has been more than a month and the refrigerator still works well. I believe the thermistor did solve the problem.
The thermistor part number is W10316760
Hope this could help those who have this similar issue.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
130,312
Location
Redmond, Oregon
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