On the ceiling of fresh food section there is plastic housing attached that has the controls - - about halfway back you'll see a small hole right above the hole is the defrost timer . You can a screw driver in there and engage the " knob " of the timer and slowly turn it clockwise until you hear " click " This will be the defrost position and the defrost heater should come on ( unless it's all ready been defrosted by you ) If it does here's the part # XXXXX which you can get from www.partselect.com. Thanks for using justanswer.
I checked the thermostat while waiting
It was 240K OHMS warm or Cold (immersed in a bag of wet ice for 10 min)
Should I replace that before trying the circuit board ?
If you're talking about the defrost thermostat ( it is attached to the evaporator coil ) a bag of ice is not cold enough to make it close ( needs to be about 20 degrees before it will close ) -- opens at about 60 degrees. Let your refr. again and get cold then turn the defrost timer into defrost like I previously described and see if the defrost heater get's hot - - if not then replace the defrost thermostat.
I cannot see any opening for a screwdriver there.
I will remove the plastic cover and report back.
Is this the unit you mean ? Sorry its big, you may have to use the sliders or adjust your screen res to higher
I think so ( you're right - rather large ) It will a 4 wire connector white, blue, yellow and orange wires. On one side it will have a knob that you can tuirn to put it into defrost ( the down side ) Do this and if it turns on defrost heater ( if freezer is cold enough ) then replace it.