Whirlpool GB2FHDXWB00 bottom freezer refrigerator, 4 years old...... freezer keeps icing over, refrigerator gets warm. Manual defrost through control panel works. Repeat problem. Repair service has defrosted refrigerator, replaced thermostat, replaced freezer thermistor (twice), added section of heating wire from defrost coil to inside of defrost drain tube.
Other than the above parts, what else is in the defrost system on this refrigerator? I did not see a separate defrost timer on the wiring diagram. This is getting quite frustrating.
I was thinking of replacing the control circuit board when I noticed on the wiring diagram that this refrigerator may have two thermistors, one for the freezer and one for the refrigerator section. Where is the refrigerator thermistor located and how do I access it? For that matter, where is the control board located and how do I access it?
It seems to me that since the defrost system appears to work, when manually initiated, that the defrost system components work when commanded "on". Besides the control board, what else might command the defrost system "on"?
Also, is there available an actual shop repair manual for this refrigerator?