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FIXED WRV986FDEM01 Whirlpool Refrigerator section is warm evap coil icing up, already replaced main board.

dohcsvt

Premium Member
Joined
Aug 8, 2021
Messages
11
Location
Suffolk, Va
Model Number
WRV986FDEM01
Brand
Whirlpool
Age
1-5 years
Hello all. I posted a thread a few weeks back about a similar problem that I thought had been corrected, but sadly I was wrong. My WRV986FDEM01 started getting up to the mid fifties in the RC section. I disassembled and found evap completely froze up. Ran the diagnostics and everything checked out SAT. Found a similar thread on here and it was his main board. I ordered a main board and replaced it and i thought the problem went away.

Then I noticed the RC fan seemed to be running ALL the time, (i can be really particular about things). Ran diagnostics and it appeared that the damper was bad because the airflow in the upper RC never ceased, but I did here clicking from behind the back panel. This is what I posted the thread on here about. I replaced the damper and checked it before complete reassembly. That is when I realized where the alternate airflow was during the diagnostics and even though the new damper was working properly, I was still getting significant airflow in the upper RC compartment, so I feel that I may have unnecessarily replaced a part. :(

Anyway, now temps are rising again (high 40s) and I can see frost at the bottom of the evap coil when I pull the drawer inserts out and look. I am near my wits end. There can't be much more to replace? The fan works great I know that for a fact, the only thing I can see is a thermistor? I figure that replacing the thermistor will be much cheaper than calling a repair person at this point since I already did the main board. My only question is how does the RC evap coil defrost? The freezer has a defrost heater, but the RC does not, so I am not sure how it defrosts. Also, the diagnostics show the thermistor is fine, so that confuses me. I hope that somebody can please provide some insight. Thanks in advance any help you may provide.
 

rickgburton

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dohcsvt

Premium Member
Joined
Aug 8, 2021
Messages
11
Location
Suffolk, Va
Yes, it’s the damper operating the way it is supposed to. Which is part of the reason I now think I replaced it unnecessarily.
 

Jake

Appliance Tech - Admin
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My only question is how does the RC evap coil defrost? The freezer has a defrost heater, but the RC does not, so I am not sure how it defrosts.
The RC thermistor and RC fan motor make it defrost.

There is a service bulletin on this problem, I posted it in this thread here:
Download that service bulletin and move your thermistor to where it tells you to move it and you should be back in business.

Remember to put your evaporator cover back in place when your done or it will not cool or defrost properly.:)

Jake
 

dohcsvt

Premium Member
Joined
Aug 8, 2021
Messages
11
Location
Suffolk, Va
Jake, you sir, are a wealth of knowledge thank you so much! I will be performing this action this weekend.
I do have a couple questions.
1. What could cause this problem to just start now after 4 years of ownership?

2. Would it be in my best interest to just buy a new thermistor when I perform this alteration?

3. Is it common for people to not put the evap cover back on? I mean it’s a PITA getting it on and off but it seems pretty intuitive that it needs to be in place.

thanks again for all of your knowledge!
 

Jake

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Location
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I'm attaching your tech. data sheet below.

1. What could cause this problem to just start now after 4 years of ownership?
Could be the thermistor is just bad.

2. Would it be in my best interest to just buy a new thermistor when I perform this alteration?
Get into diagnostics and DO--->Service Test - 39 RC Evap Thermistor--->The board will check the resistance value of the thermistor and display the results on the Temp Display. (01 = Pass, 02 - Open, 03 = Short.

The RC evaporator thermistor ONLY comes with the FRESH FOOD EVAPORATOR FAN MOTOR.

Here's the FRESH FOOD EVAPORATOR FAN MOTOR for your model you can order:
Evaporator Fan Motor W11087438


3. Is it common for people to not put the evap cover back on? I mean it’s a PITA getting it on and off but it seems pretty intuitive that it needs to be in place.
Its a MUST, CUT AND DRY:)

Jake
 

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dohcsvt

Premium Member
Joined
Aug 8, 2021
Messages
11
Location
Suffolk, Va
Just got around to doing this today after my new fan assembly arrived. The thermistor in my unit was already in the location noted in the service bulletin, I guess it was built after the bulletin was put out. I am going out of town for about a week. I will report back on what I find when I return, hopefully good news. Additionally, I found this video that also talks about the defrost cycle time which I will set as noted once I get the unit reassembled.
 

dohcsvt

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Aug 8, 2021
Messages
11
Location
Suffolk, Va
Additionally, before I reassembled the whole mess I decided to do some more trouble shooting. The plastic thermistor on the new fan unit shows about 3k ohms, the metal one also shows about 3k ohms. On the unit I took out the plastic is about 3k ohms but the metal is about 12k ohms. It’s resistance changes with temp, but I suspect that was the culprit. I wonder why the diagnostics on the fridge said it was good. Could have saved me over $300 in parts as I already replaced the card and the damper. I guess I should have performed more in depth trouble shooting before I started Easter egging parts…☹️
 

Jake

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Location
McMullen Valley, Arizona
Yes, that is odd that the control board said the old ones passed.

So it looks like you had 2 problems, bad control board sending wrong information about the bad metal thermistor, and bad metal thermistor, which is the evaporator thermistor.

So now you should have a working refrigerator, fingers crossed.🤞

Jake
 
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