Check the exhaust vent system for obstructions. There are restrictions on the exhaust vent system to the outside of the home. If the exhaust vent system is clear, you can measure the resistance of the inlet and outlet thermistors with a multimeter. The temperature at which the outlet thermistor should measure should be 70 degrees. The temperature at which the thermistor should be measured is 70 degrees. There are thermistors that need to be replaced.
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