GE GSS20IBTAWW - Not defrosting

[ciwa]

Hello,

I have a GE GSS20IBTAWW side-by-side fridge that is not defrosting. I disassembled the panel and found a block of ice behind the freezer back panel.  I have seen this in a different fridge and had to change a thermistor which was bad.

I am assuming this is a similar problem where the motherboard is reading a high temperature value and not starting the defrost cycle, but assumptions are what they are...

Can anyone help me in telling me which pins/connectors represent the thermistor inputs for this fridge and what I should be reading?

thanks!

Ciwa

[ciwa]

My post should read "which pins/connectors represent the thermistors' outputs on the motherboard" 

[darren412]

at the J1 connector usually its the 4th and 5th pin connection  that are the evaporater thermistor pin connections.    If its frozen in ice at the evaporator already , then all you need to do is pull the fridge out and un plug the J1 connector.  The top and farthest connection to the right.   Place the black lead in the 5th pin connection at the unplugged harness  and  place the red lead in the 4th pin connection at the unplugged harness.  you should be reading about 16.3 K ohms  (16,300 ohms)  + or - 5%     if your not within those specs then replace the evaporator thermistor.    If the evaporator has already been defrosted. Pull the thermistor out enough to get it into a glass of ice with a small amount of water supported on top of the evaporator some how. This just keeps you from cutting out the thermistor to do this same test and then not worrying about having to splice together the thermistor wires if the thermistor is ok.  Check it after 10 min.  one more thing.  Verify wether its good or bad first and then if you notice the wire end of the thermistor has a black sealant, then you want to replce any thermistors that are like that anyway.  GE had an issue with some of those Black ended thermistors. 

[ciwa]

Thanks for the super good lead.  I have started to defrost the whole thing to actually see the thermistor.

i did take some measurements once defrosted and I get about 6kohms on those, but I'll do the glass of ice water trick to see what I get in that situation and check for the black ended thermistors. i also remember something about a flat ended versus round ended thermistors... was that the same issue?

Anyway, If they do check out ok, how do I check the defrost can indeed work? I guess that would also be important

[darren412]

if the bi metal t-stat on the evaporator is in the ice and frost then that  T-stat should be closed . the t-stat needs to be closed in order to test the defrost heater from the board.  These tests are usually done right when the evaporator is encased in the frost and ice.   So if you know through testing that the bi metal t-stat is closed  , you then can go to the bottom of the mother board and there is a blue connection , connected to J8 , J9, and J11 on the board.     J11 is the line voltage and J9 is for the defrosting cycle.  Put a well insulated jumper wire from J11 to J9 and the heating element should heat up.   If it doesnt then you either have a bad t-stat or a bad heater. It is a quick way of telling you the heating element and bi metal t-stat is ok and as long as the evaporator thermistor specs are good , then the mother board will be suspect.  . Be aware that GE heating elements can also give false readings sometimes because the moisture gets in the glass tube element when it fails at times and then it gives you a false reading even though  its a bad heating element.  Doesnt happen alot but can happen when testing with a meter. not sure about the flat ended and round ended thermistors but just make sure they are the all white thermistors and if the specs are good , you should be ok.  the evaporator thermistor is the one thats for the defrost cycle. the other thermistors will have nothing to do with the defrost cycle.

Edited September 20, 2019 by darren412

[ciwa]

Thanks again for all this great info! 

I have had the thermistor in a glass of ice water for well over 20 minutes now and it reads 12.10 k Ohms.  And it's got a black sealant.  I will start with replacing that and see what happens.

[darren412]

yeah sounds like the evaporator thermistor is bad.  Not that its a concern for the defrosting cycle but The freezer and fresh food compartment thermistors are most likely the black ended ones also. Once you know the defrost cycle has been fixed. change out the other thermistors also if they are black ended . that will eliminate any future issues with those also.

Edited September 20, 2019 by darren412