中文
含义
F25 表示干衣机排气口热敏电阻（出风口温度传感器）信号异常。与位于进风道的 F22 传感器不同，F25 涉及的排气口热敏电阻安装在出风管道出口处，用于监测经过滚筒后排出机外的湿热空气温度。主控板通过该传感器判断烘干进程——当衣物接近干燥时，出风温度持续上升；当达到目标干燥度时，温度趋于稳定。该传感器同时承担过热保护功能：若出风温度超过安全阈值（通常为 95–105 °C），主控板将立即切断加热元件。当排气口热敏电阻信号异常时，机器无法准确判断干燥终点，可能表现为衣服未干就停机或过度烘干。
常见原因
- 排气口热敏电阻探头表面被棉絮和织物纤维严密包裹，传感器无法直接接触排出气流，读数严重偏低。
- 出风管道内部棉絮堆积多达管径的一半以上，气流受阻导致排气温度异常升高，长期过热使传感器性能衰退。
- 热敏电阻线束在出风管道高温区段长期暴露，绝缘层熔化导致内部导线与金属管道壁短路。
- 排气风道连接处的密封垫破损，高温潮湿气体泄漏到机器内部，传感器实际测量的是泄漏后被稀释的气流温度。
- 热敏电阻插接件因冷热循环导致塑料壳体变形或触点回弹力丧失，接触电阻增大，信号衰减。
- 主控板排气热敏电阻输入端的分压网络故障（如贴片电阻焊点微裂纹），造成 ADC 采样值在有效范围内随机跳动。
- 机器排气管道过长、弯头过多或室外排风口被鸟巢/杂物堵塞，排气背压过大，出风口温度远超正常工作范围。
自助排查
- 断开干衣机电源，找到机器后部或侧面的排气管道接口（通常为直径 10 厘米的圆形金属口）。拧开管箍，取下排气管道，检查管道内部棉絮堆积情况——集中清理整段排气管道至室外出口。
- 在排气管道接口内侧找到排气口热敏电阻（通常为细长金属探头，伸入出风气流中）。目视探头表面，用软布擦除棉絮和油污层。注意探头较脆弱，切勿用金属工具刮擦。
- 用万用表电阻档测量排气口热敏电阻的室温阻值，一般与进风热敏电阻规格相同（10 kΩ–50 kΩ @25 °C）。若测得的阻值在室温下稳定且在合理范围内，进行下一步加温测试。
- 使用电吹风中温热风挡（约 50–60 °C）对着探头吹 20–30 秒，同时观察万用表阻值是否持续下降。若阻值无变化或跳变不连续，说明热敏电阻内部断裂，需更换。
- 检查排气口热敏电阻的线束路径：确保线束不接触滚烫的出风管道壁，不与滚筒或皮带摩擦，插接件牢固。如发现线束周围有熔融塑料痕迹，应更换整根线束。
- 确认室外排气出口无遮挡——检查外墙排气帽的百叶窗是否被鸟巢、树叶或结冰堵塞，排气帽应能自由打开排风。
- 若传感器、线束和排气管道均无问题但仍报 F25，故障点可能位于主控板的对应输入通道。请联系肯摩尔售后服务，由专业技师使用故障诊断仪读取实时传感器数据，对比确认后更换主控板或传感器。
English
Meaning
F25 indicates an abnormal signal from the dryer’s exhaust outlet thermistor (exhaust air temperature sensor). Unlike the F22 sensor located in the intake air duct, the exhaust outlet thermistor covered by F25 is installed at the exhaust duct outlet and monitors the temperature of the hot, humid air exiting the machine after passing through the drum. The main control board uses this sensor to determine drying progress — as clothes approach dryness, the exhaust temperature rises steadily; when the target dryness level is reached, the temperature stabilizes. This sensor also provides overheat protection: if the exhaust temperature exceeds the safety threshold (typically 95–105 °C / 203–221 °F), the main control board immediately cuts power to the heating element. When the exhaust thermistor signal is abnormal, the machine cannot accurately determine the end of the drying cycle, potentially resulting in clothes remaining damp when the cycle ends or excessive over-drying.
Common Causes
- The exhaust thermistor probe surface is tightly wrapped with lint and fabric fibers, preventing the sensor from directly contacting the exhaust airflow and causing severely low readings.
- Lint accumulation inside the exhaust duct exceeds half the duct diameter, restricting airflow and causing abnormally high exhaust temperatures; prolonged overheating degrades sensor performance.
- The thermistor wiring harness has been exposed to high temperatures in the exhaust duct hot zone for extended periods, with insulation melting and causing internal conductors to short against the metal duct wall.
- The gasket at the exhaust duct connection has deteriorated, allowing hot, humid air to leak into the machine interior; the sensor is actually measuring the diluted temperature of leaked air.
- The thermistor connector housing has deformed from repeated thermal cycling or the contact spring force has weakened, increasing contact resistance and attenuating the signal.
- The voltage-divider network at the main control board’s exhaust thermistor input has failed (e.g., micro-cracks in surface-mount resistor solder joints), causing the ADC reading to fluctuate randomly within the valid range.
- The exhaust duct run is excessively long, has too many elbows, or the outdoor vent termination is blocked by a bird nest or debris, creating excessive exhaust back pressure and driving outlet temperatures far beyond the normal operating range.
Self-Check Steps
- Disconnect the dryer from power. Locate the exhaust duct connection at the rear or side of the machine (typically a 4-inch / 10 cm round metal port). Loosen the duct clamp, remove the exhaust duct, and inspect the duct interior for lint accumulation — thoroughly clean the entire exhaust duct run all the way to the outdoor termination.
- Locate the exhaust thermistor inside the exhaust duct connection (typically a slender metal probe extending into the exhaust airflow). Visually inspect the probe surface and wipe off lint and oil residue with a soft cloth. The probe is fragile — never scrape it with metal tools.
- Using a multimeter in resistance mode, measure the exhaust thermistor’s room-temperature resistance. It typically matches the intake thermistor specification (10 kΩ–50 kΩ at 25 °C / 77 °F). If the reading at room temperature is stable and within range, proceed to the heating test.
- Use a hair dryer on a medium-warm setting (approximately 50–60 °C / 122–140 °F) to blow warm air on the probe for 20–30 seconds while observing whether the multimeter reading decreases continuously. If the reading does not change or jumps discontinuously, the thermistor has an internal break and must be replaced.
- Inspect the exhaust thermistor wiring harness routing: ensure the harness does not contact the hot exhaust duct wall, does not rub against the drum or belt, and that the connectors are secure. If melted plastic traces are found around the harness, replace the entire harness.
- Verify that the outdoor vent termination is unobstructed — check whether the louvered flaps on the exterior wall vent cap are blocked by a bird nest, leaves, or ice. The vent cap should open freely to exhaust air.
- If the sensor, harness, and exhaust duct are all fine but the F25 code persists, the fault point may be on the corresponding input channel of the main control board. Contact Kenmore after-sales service so a professional technician can read the real-time sensor data with a diagnostic tool, compare and confirm, and then replace the control board or sensor as needed.