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FIXED WRV986FDEM01 Whirlpool Refrigerator Evaporator icing

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ddbama

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Model Number
WRV986FDEM01
Brand
Whirlpool
Age
1-5 years
My refrigerator model WRV986FDEM01 began experiencing loss of cooling in the freezer and refrigerator sections 2 weeks ago. Upon disassembly I discovered the evaporator coils were completely frozen with ice and the evaporator fan was hitting the ice that formed. I defrosted the evaporator using a hair dryer and the refrigerator and freezer returned to normal operation. 1 week later I heard the evaporator fan hitting ice again and I checked the refrigerator and freezer temps and found they had increased. Upon disassembly the evaporator was found iced up again (see attached picture). I defrosted the evaporator again and the unit returned to normal operations. I ran the service diagnostic tests for the defrost heater and thermistor and both passed. Any ideas what could be causing the evaporator to ice up like this? I’m assuming it is a defrost issue but the service diagnostics did not indicate any issues unless it is a control board issue. What else can I check before ordering a new main board?
 

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rickgburton

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ddbama

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Thanks for the part reference. Are you indicating this is most likely a control board issue? Is there anything else I can check before making a $350 purchase for a new control board? What in the control board could be causing this if the refrigerator is functioning normally except for the icing of the evaporator? Would running the forced defrost in the service mode tell me anything about the potential issue?
 

rickgburton

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Only 3 parts make up the defrost system. The control board uses the input from the thermistors to know when to start a defrost cycle. If the defrost heater and thermistor check good, replace the control board.
 

ddbama

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Thank you again for the response. If I enter the service diagnostic mode,turn on the forced defrost, and the defroster starts heating does this indicate that the defrost system is functioning properly and I have another issue? Or could the forced defrost function properly with control board issues? Just want to make sure I truly have a defroster issue and it is tied to the control board before I purchase the $350 part. Thanks!
 

Jake

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If I enter the service diagnostic mode,turn on the forced defrost, and the defroster starts heating does this indicate that the defrost system is functioning properly and I have another issue? Or could the forced defrost function properly with control board issues?
Rick should be here soon, but that means your defrost heater and defrost thermistor are good, and the problem is in the control board.

Jake
 

rickgburton

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If I enter the service diagnostic mode,turn on the forced defrost, and the defroster starts heating
In service mode the control board bypasses the thermistors input. The defrost element is like a light bulb, it's either good or bad. The thermistors are a variable resistors. If the element and thermistor check good, control board is bad.
 

ddbama

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Ok I pulled the back freezer cover off again after one week since the last manual defrost and found the evaporator in the condition shown in the attached picture. Not as much ice as previous but still iced up more than I would expect is normal. I tested the defrost heater with my multimeter and it confirmed the service mode diagnostic test was correct (no issues). I then attempted to put the system into forced defrost mode (cycled from off to short in test 38) but the heater never turned on. Is this expected if there is a control board issue?
 

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rickgburton

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Is this expected if there is a control board issue?
Nothing is "expected" from a failed part. Put the machine into a defrost cycle and measure the voltage on the main board between P2-7 and a white neutral wire.
 

ddbama

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When I go to service test 38 and press the SW3 button to place the system in forced defrost mode it only allows me to cycle to “Sh” but not “Lo.” Once I press SW3 and I see Sh blinking should forced defrost mode be running and the heater on of the system is working or do I need to select another button for it to start? Any thoughts why when pressing SW3 on test 38 it only cycles between “Of” and “Sh”?
I am going to test the voltage on the main board once I verify I’m attempting the forced defrost cycle correctly.

thanks again!
 

rickgburton

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Do this: Use a hair dryer and completely defrost the evaporator. Make sure the evaporator cover is installed. After 24 hours with few door openings, leave the machine plugged in and running, remove the evaporator cover and take a pic of the frost pattern on the evaporator coils and post it here. Thanks.
 

ddbama

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I re-ran service test 38 (forced defrost) and the defrost system turned on! I pulled the back cover and confirmed the heater turned on and melted the ice build up that formed (same amount of ice present that developed in the previous week). Previously I didn’t realize you had to exit the service mode with “Sh” selected before the forced defrost mode actually turned on.
So it sounds like I truly do have a control board issue.
Now that the system is defrosted I’ll check the ice build up that forms after 24 hours and will report back.
How often do I need run the short defrost cycle In the mean time while I’m waiting on a replacement board so that I can prevent ice from building up?
 

ddbama

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Ok let me ask the question another way: what frequency would the defrost cycle normally run to prevent ice? I would prefer to not have to pull apart the freezer to determine when I need to run a defrost cycle while I wait in a new control coated to come in.
 

rickgburton

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It uses adaptive defrost. The control uses the information from the thermistors and keeps track of compressor run time and length of time the defrost heater remained on the last time along with door openings to know when to start a defrost cycle so anywhere between 9-99 hours. If the control board makes it in the next few days you don't need to force a defrost cycle.
 

Jake

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That's exactly my thoughts too, it takes about 5-7 days for it to get massive frost build up on it again, so don't worry about defrosting it till you get the control board.:)

Then defrost it when you replace the control board.

Jake
 

ddbama

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Received my new control board, but can’t find programming instructions for this model refrigerator. Can you assist?
 

ddbama

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Thanks! Just put the new board in and “PF” was displayed on the main display. I selected “Confirm” and everything seems to be functioning so far. Are there any tests I should run to ensure everything is operating properly?
 

rickgburton

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Are there any tests I should run to ensure everything is operating properly?
No, The refrigerator needs 24 hours for temperatures to stabilize.
 
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