u/Appropriate-Run748

Hi all I have a whirlpool top freezer refrigerator (wrt318fmdb01) that was cooling intermittently and not defrosting. I tested the defrost heater and thermistor and they both tested good so I replaced the board with a refurbished board and things seem to be improved but it's still not 100% right. It's been over 2 weeks with the new board. One of the things that improved is with the old board the freezer would be completely frosted up, now there's very little frost. Another thing was when I ran the forced defrost with the old board it kept kicking it out of defrost mode after 10-15 minutes. It doesn't do that with the new board. Also, when I ran diagnostics using the old board, the first light would come on after diagnostic, now the middle light (normal operations?) light comes on after diagnostic.

I researched my model number and it says there's a defrost bimetal thermostat that could be bad (2nd picture). The problem is I can't find a defrost bimetal thermostat in my unit. At least not the part that it's saying I need (3rd picture). From the first picture of the freezer compartment, what's that small black plastic part on the left side? Could that be some type of thermostat that's different from the part I thought I need? Based on more research it seems like the thermistor is an advancement over the defrost thermostat so my fridge wouldn't have both? Could it be a thermistor that tested good but doesn't work right under load? Could it be the refurbished board and I need an OEM board? Could it be something else entirely? Hate to drop $300 on an OEM board for a 8+ years old fridge from when I bought it (10 years from manufacturing date). Thanks for your help.

Hi all, I have a whirlpool top freezer refrigerator that was not defrosting and causing temperature fluctuations, fridge goes between cool and warm, freezer would thaw and refreeze. I did the following:

ran forced defrost mode and the defrost heater turned on and got hot so I figured it's good. One interesting thing is it kept going out of forced defrost mode after 5-15 minutes. I had to run it multiple times to completely defrost the freezer. Each time I ran it lasted longer than the previous time.
tested the thermistor and got recommended ohm readings at room temperature and in ice water, respectively, so figured it was good
based on items 1 and 2 above, I replaced the control board. I did get a refurbished one instead of new because the fridge is 10 years old and I didn't want to drop $300 on a new board, especially since it could be something else.

It's been over 24 hours and it seems better than before but it still went through one thaw/refreeze cycle. Do I need to give it more time or is it something else?

Thank you

Whirlpool top freezer refrigerator intermittent cooling