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I have a Frigidaire refrigerator (FGHF2366PF3), freezer slides out on the bottom with dual doors on top for the fridge. The freezer stays cold (-18c), but the fridge will not (13c last I seen). I’ve been troubleshooting and trying to figure it out, I checked and made sure that the evaporator fan works. I removed the back cover in the freezer and can confirm there was quite a lot of ice all over the coils, and from my research that tells me it’s an issue with the defrost system. I placed the freezer into manual defrost mode by holding the + and - buttons for 5 seconds or so, then watched to see if the heating element would heat up and melt the ice, but it did not. I checked the continuity on the main board for the heater to see if the connection was broke. While keeping everything plugged into the board my multimeter reads 190Ω, if I disconnect the plugs from the main board and measure then the resistance reads 4mΩ (and kept increasing while measuring). Does this sound right? EDIT: The ice finally melted enough for me to access the wires coming off the heater (instead of measuring at the main board), directly to it my multimeter beeps and says 026.6Ω, so I’m really not sure why it would not be heating up when receiving voltage? I then tested the same wires on the main board but for voltage, as soon as I put the fridge into manual defrost mode the reading went straight to 122VAC, telling me it’s getting power, but still not heating up. Next I checked the defrost thermostat which I seen the seal around part of it looked pushed up. I tested it at room temperature and it was open, then I read to test it by putting it into a glass of ice water, but it still remained open (measured several times every minute or so for a while), so I believe the thermostat is broke and needs to be replaced. Even if the thermostat is broke, wouldn’t the heater still work when manually put on (and I know I’m getting voltage going to it)? Any info is greatly appreciated, I’m comfortable working on things like this but definitely not an expert with refrigerators. Update (12/14/2019) After taking another look at the wiring diagram I see that the defrost heater connects to the thermostat, so if the thermostat is stuck open then it would make sense that electricity could not pass through it to complete the circuit. Now it would make sense seeing as I have continuity and voltage at the main board. I’m pretty sure I’m correct on this and will be ordering a new thermostat but if anyone is able to confirm it in the mean time that would still be appreciated, thanks!
Hi @nand , The defrost thermostat in most refrigerators is designed to operate at about 32 -33 F (0 - 1 C) and cut off the power to the defrost heater so that the evaporator unit does not get too hot and possibly can be damaged during the defrost period. During the defrost cycle, the compressor is stopped and the temp in the freezer is allowed to rise to 32 F (0 C) so that any ice formed over the evap unit melts and is drained away to evaporate outside the refrigerator compartments. The defrost heater is used to speed up the melting process so that any frozen food does not start to thaw. Once the defrost cycle is over and the temperature starts to go back down to 0 F (-18 C) the defrost thermostat resets and is ready for the next cycle.
