Your refrigerator has what they call adaptive defrost control ADC fer short. Aint no timer like older models have. To force a defrost the light switch must be toggled
Frigidaire A.D.C (Automatic Defrost Control) – Adaptive
To initiate defrost cycle toggle Fresh Food light switch - 5 times in 6 sec.
- To cancel defrost cycle toggle F/Food light switch - 5 times in 6 sec.
- After defrost cycle test cancellation, compressor runs immediately, 1 min. delay for evaporator fan.
- After regular (non "forced") defrost – 6 min. delay for compressor
- 7 min. delay for evaporator fan
- Vacation mode: if heaters on for less than 6 min. or F/Food door not opened for 24 hrs -------- then 72 hr. defrost timing interval is set up. When door later opened, defrost reverts to previous pattern.
This adc board basically goes by how many times you go in and out the ice box. When it gets to x amount of door openings it figures enough air done got inside that ice box to form some frost on there. So she-boom it kicks into a high gear defrosting cycle. If you don't be messing with that ice box then them board sees fit to not worry too much about defrosting fer a while. The basic heater and terminator(that's a defrost heater thermostat) is the same as the old style and both work the same. I would say if you cannot force defrost and both the heater has continuity and the defrost termination thermostat has continuity when at a temp of 25f of lower then you should just replace that board. It is located behind the light bulb and cold control within that array. Very easy to get to. I have always said all that cold damp air was too much on them fancy boards; too easy for corrosion to set in. Yank yours out and clean the corrosion off of them contacts and retry before you buy.Git you one