How does the dryer determine that the blocked vent icon needs to be turned on? There is no air flow meter. Every post I have seen tells me to clean the vent, check the fan and etc.... But, were is the sensor that detects it? I need to check the sensors that are setting this off. I have also checked and cleaned the moisture strips in the dryer, replaced the exhaust thermistor. There is an input thermistor but, no one knows how to check it to see if it is bad. Thanks