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KRFF507ESS01 - Moved thermistor but ice still building up on the evap coils

gmchusyr

Premium Member
Joined
Dec 30, 2019
Messages
3
Location
DC
Model Number
KRFF507ESS01
Brand
KitchenAid
Age
1-5 years
This post is regarding KitchenAid refrigerator model KRFF507ESS01 no longer cooling in the refrigerator section due to ice buildup on the evaporator coils. About 4 months ago, I completely defrosted the fridge and relocated the thermistor as recommended in the service bulletin (see attached picture, I'm not sure if it matters if the thermistor is attached to the inner or outer tube). I also set the defrost mode to 02 - basic mode on 8 hour timer. Fast forward to today, the refrigerator is no longer cooling and surprise, surprise, the evap coils are iced up again.

I'm not sure where to go from here so I'm hoping someone can help me out. I can confirm that the fan above the evaporator coils is working. I'm thinking a next step is to replace the thermistor, however, doesn't setting the defrost mode to the 8 hour timer bypass the need for the thermistor? Also, how would I go about replacing the thermistor? I noticed the two black thermistor wires lead into a shared connector (see 2nd pic of connector). Any help would be greatly appreciated.
 

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Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
107,785
Location
McMullen Valley, Arizona
Hi,

Ok, there is no defrost heater on the fresh food evaporator coil, only the freezer evaporator coil has the defrost heater. This is a very complex dual evaporator cooling system with the 3-way involved.

This how it works:
If the refrigerator compartment is calling for cooling the control determines if the refrigerator evaporator coil temperature has been above a predetermined temperature (approximately 35°F) for 15 minutes. This is to assure the evaporator coil is
defrosted.
- If the evaporator coil is below the predetermined temperature the refrigerator fan turns on to circulate air over the evaporator coil to defrost it. The fan will operate until the evaporator coil is above the predetermined temperature for 15 minutes.
- If the evaporator coil is above the predetermined temperature but for less than 15 minutes the refrigerator fan turns on to circulate air over the evaporator coil to defrost it. This continues until the 15 minute time is met.
• When the evaporator coil is above the predetermined temperature for 15 minutes or more the 3 way valve moves to the closed position. At the same time the compressor, condenser fan, refrigerator evaporator fan turn on.
• With the 3 way valve still in the closed position the compressor evacuates the refrigerant from the low side of the system and pumps it into the high side of the refrigerant system.
• After a predetermined time (approximately 2 minutes) the 3 way valve changes position allowing refrigerant to flow from the high side, through a capillary tube, and into the refrigerator evaporator coil allowing cooling of the refrigerator compartment.
The refrigerator evaporator fan also turns on and circulates air across the evaporator coil. Heat is removed from the air and recirculated back to the compartment.
• When the refrigerator temperature cools below the control setting it will either:
- Turn the compressor, condenser fan, and evaporator fan off and switch the 3 way valve to the open position.
- Or, if the temperature in the freezer compartment is above the control setting or is within a predetermined amount from the cut in temperature the 3 way valve changes position allowing refrigerant to flow from the high side, through a capillary
tube, and into the freezer evaporator coil allowing the cooling of the freezer compartment. The freezer evaporator fan also turns on and circulates air across the evaporator coil. Heat is removed from the air and recirculated back to the
compartment.

So if the refrigerator evaporator fan is running, and you moved the the thermistor to the proper position, and put the control board in 8 hr defrost instead of ADC, then I really don't have a clue why it's still frosting up your refrigerator evaporator coil. Unless there is a problem with that 3-way valve sticking and allowing the refrigerator evaporator coil to get a CONSTANT flow of refrigerant through it and not closing that 3 way valve to the refrigerator evaporator after the temperature in the refrigerator has been satisfied.

I'd suggest having Whirlpool come out to see if it is that 3-way sticking open for the refrigerator evaporator coil.

Jake
 

gmchusyr

Premium Member
Joined
Dec 30, 2019
Messages
3
Location
DC
Hi Jake,

Thanks for the reply. Does the fan reverse operation for defrost and cooling? From what I can recall, it seemed like it was blowing upwards towards the center channel. I did not check to see if it blows downwards towards the coil. Should I hear the fan turn on when I initate a long defrost through the service menu? Would any of the tests in the service menu tell me if there's an issue with the fan? I did the tests for the thermistor and they all seemed to pass.

In regards to contacting Whirlpool, I will probably take my business elsewhere. I found their customer service to be dishonest and unhelpful. When they denied my inquiry for a goodwill warranty (only a couple months out of warranty), I told them that this seemed to be a widespread issue with this model. They put me on hold to do some research and said there were no similar issues they could find and that there were no active bulletins. I then stumbled upon this site and found the service bulletin regarding the thermistor.
 
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gmchusyr

Premium Member
Joined
Dec 30, 2019
Messages
3
Location
DC
Also, for any other DIYers attempting to disassemble this fridge, you have to remove the ceiling and center channel to remove the bottom evap cover without breaking it. It's held on by two tabs that are only accessible by removing the center channel (see pic). In general, the parts are very delicate and don't take much force to break. I also managed to snap one of the tabs holding the deli cover in place. This fridge has been such a headache to own.
 

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Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
107,785
Location
McMullen Valley, Arizona
Unfortunately, I don't know the answers to those questions, I have not run into this problem before on my local service calls as of yet.

I'd contact the Whirlpool Corporate office and let them know: http://www.whirlpoolcorp.com/contact/

Here is their corporate address:

Corporate Headquarters
Administrative Center
2000 North M-63
Benton Harbor, Michigan 49022
Phone: 269.923.5000

Ask for Marc Bitzer, he is the CEO, most of the time you may not reach him personally, but his secretary can take your call and information and the message will get to him and you should see good results.

These 2 members did with good results:
SF368LEPQ1 Auto-clean on gas range melted clock/control panel
KUDI01FL Dishwasher, not working, thermal fuse ok

Jake
 

Blumin1

Member
Joined
Jan 21, 2020
Messages
1
Location
Louisiana
Any luck resolving the ice build up? I'm experiencing the same issue. I've manually defrosted the unit 3 times in the last year.

Do you have a link that describes how to reset the defrost mode?
 

ostbloom

Premium Member
Joined
May 22, 2019
Messages
7
Location
Louisville, KY
KRFF507ESS01. Mine does the exact same thing. Thermistor moved, long defrost, fan works (even though I replaced it and the thermister as a precaution), doors adjusted properly, new drain hose. Freezes up about every 3 months. Why they didn’t install an electric defrost just astounds me. After spending almost $4000 on all new Kitchen Aid appliances a couple years ago, I concluded I would never buy them again. Good luck everyone.
 

ostbloom

Premium Member
Joined
May 22, 2019
Messages
7
Location
Louisville, KY
To put it into manual defrost, enter troubleshooting mode By pressing far Left 2 buttons at the same time (called 1 and 2). Then move to #38 by pressing +. Then press 3 until you see LO (for long) and then get out by pressing 1 & 2 together.
 

ostbloom

Premium Member
Joined
May 22, 2019
Messages
7
Location
Louisville, KY
I’ve owned mine for 5 years. Froze up 10 times. I replaced the fan, moved the thermistor, adjusted the defrost cycles, everything. Froze up the other day so I ordered a new drain hose. Pulled the old one off and it was clogged up solid. I never would have thought that was it but it was. Hopefully that will solve it.
 

ostbloom

Premium Member
Joined
May 22, 2019
Messages
7
Location
Louisville, KY
I’ve owned mine for 5 years. Froze up 10 times. I replaced the fan, moved the thermistor, adjusted the defrost cycles, everything. Froze up the other day so I ordered a new drain hose. Pulled the old one off and it was clogged up solid. I never would have thought that was it but it was. Hopefully that will solve it.
Nope, froze up again.
 
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