My GE GSH25JFTFBB side by side is not defrosting properly. I have already replaced the motherboard & defrost heater element, and have manually defrosted several times. Evap coils continue to frost over and cut off cool air to fridge. My local repair guy (via phone) says it could be the Bi Metal. Another source online suggested replacing thermistors. What do you think?

Bypass the defrost timer by jumping it and applying current directly to the defrost heater element.

If you are showing a frost pattern iside the freezer and higher temperatures in fresh food compartment that is a sign of defrost failure. What is happening is the airflow to the fresh food section is being restricted by a large blok of non defrosted condensate behind the rear pane you see the frost pattern own. I am sending a manual if you like to follow along and ask questions but as I see from your discription this is what most likely happening. Your model does defrost cycle through the motherboard and has no defrost timer. So the most likely cause is you Defrost heater or defrost thermostat are defective. Here is the heater and instructions on how to test heater Click Here=> WR51X322 Heating Element and Defrost Thermostat=> WR50X10088 Defrost Thermostat


Here is the service manual=> GE Monogram Refrigerator Service Manual
You can find those two part numbers here also=> WR51X322 Defrost Heater
and Defrost Thermostat Here=> WR50X10088 Defrost Thermostat
Should you have any questions I will be here to assist you or on my sites, Thank You Sea Breeze
Also make sure none of the lower vents are closed inside fresh food compartment that will also restrict airflow. Manually defrost ing the freezer will give you about another week to resolve this problem should it turn out as defrost problems. You will need Adobe Reader to open the manual I sent you=> free download.

Hello,

Since the heater has continuity it is good and does not need to be replaced, the other parts that can make a ref. not defrost are the defrost thermostat or the defrost control (mother) board.

To check the defrost thermostat it must be checked when cold,when cold it should have continuity on it. The defrost thermostat is in the freezer clipped to the TOP of the evaperator coil usually on the right side...this is what it looks like

If the defrost thermostat has no continuity when cold it is bad and thusly the problem...if it is good and has continuity and already having determined the defrost heater is good..the problem is going to be the motherboard since a part of it is the defrost control.it is the back of the ref.on the left.

The part numbers are

DEFROST THERMOSTAT...... WR50X10068

MOTHER BOARD..... WR55X10942

this actually may be the defrost heater that is not working. If the heater does not work, the ice does not melt and the whole thing becomes an ice block.
This would be a job for a proffesional

The problem is most likely the defrost heater element(s) and/or the defrost timer. The defrost heater element(s) are located with the evaporator core behind the access panel inside of the freezer, and can be removed, tested with an ohm meter, (any reading other than infinity would most likely mean the heater element is functional) and replaced if necessary. The defrost timer can be located inside of the refrigerator, or outside of the refrigerator behind the front kick panel, or behind the rear access cover on the back of the refrigerator.

Usually if the evaporator core is freezing up and not allowing air to flow through the evaporator core, (necessary for the system to function properly) then the defrost timer is most likely working and the defrost heater element(s) would most likely be at fault.

Always place a towel on the bottom of the freezer and use a blow dryer to defrost the evaporator core and never use any sharp or hard objects to pick away the ice or the evaporator core can be damaged and the refrigerant will be leak from the system.

I have included some images to help assist you including an image of a defrost timer that is located inside of the refrigerator, and a new defrost heater element or defrost timer can be purchased from an appliance parts distributor.

Let me know if you require any further assistance.

Hi and welcome to FixYa. I am Kelly

I am going to paste part of your text and then reply:

Your text:

Repairman came back and replaced a small round part at the top of the evaporator (resistor??) <
{ That was the termostat}

I just read that the problem could be the defrost thermostat..

He already replaced it.

I hate to say it but is sounds like your in repairman hades.

So far I see 1. a new mother board, 2. new defrost thermostat and 3. new defrost heater element. (other than wiring that is everything in the circuit)

Either one of the 3 NEW parts is bad or...there is a partially broken wire in the circuit.

Hopefully this helps you understand. ( I know it does not fix your uint)

Thanks for using FixYa.

Kelly

P.s your words again:

one would expect this to be remedied.
You got that right!

Most likely your refrigerators defrost heater is burned out. The PSS26MRSS has no defrost timer and defrost is done when the motherboard tells it to. I have not seen may problems with the mother board when it comes to defrost. Check the rear wall of freezer for frost and if yes unplug and remove contents and rear panel in freezer. Get a hair dryer to speed things up and once the ice is melted look for the defrost heater at base of the evaporator coil. When they burn out they are easy to spot because the outer tube is glass covering the defrost element inside. If burned out replace the defrost heater and defrost thermostat. I will instruct you, Thanks, Sea Breeze

Possible defrost problem. If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air.Since you've already replaced the motherboard Checkdefrost heater, defrost thermostat
How to check everything
http://www.acmehowto.com/howto/appliance/refrigerator/refrigerator.php

In my GE side-by-side there is a defrost temp sensor located near the top of the evaporator coil. I think the control board uses that temp sensor to know when it should be done defrosting.

On the schematic of my fridge (link below), the defrost thermistor is part number 240 in the diagram (not part number 241, which is a different temp sensor located adjacent to the one you want)

http://www.partselect.com/ModelFrames.aspx?ModelID=361233&ModelNum=GSS20IEMDWW&mfgModelNum=&ManufactureID=2&Selected=00113321i06&Position=2&mfg=GE&Type=&Mark=2

I don't know why the defrost element would fail immediately other than incorrect supply voltage or just a bad defrost element.

deF error means that you need to defrost the unit. Leave the unit unplugged overnight and defrost completely.