[zatman2]

Defrost Heaters won't come on. New Motherboard 241511102. Defrost thermostat checks out OK. 30 ohm resistance across heaters measured both at the heaters and at the motherboard connector. Forced manual defrost but no voltage across J3-7 and J3-5 at motherboard (120v supply to heaters). Checked both in ADC mode (Defrost jumper open) and timer mode (Defrost jumper shorted).

[PS Staff - Sheila]

The defrost thermostat is hook in series with the heater.

If the freezer is not down to operating temperature the thermostat will be opened and current will not flow.

Here is a link to your fridge model FLSC238DS9.

[zatman2]

Defrost thermostat check out OK. Contacts closed at low temperature. Open at room temp.