A dryer appliance may include a cabinet, a drum, a heater assembly, a temperature sensor, and a controller. The heater assembly may be in upstream fluid communication with a drying chamber. The temperature sensor may be in upstream fluid communication with the drying chamber. The controller may be in operable communication with the heater assembly and the temperature sensor. The controller may be configured to initiate a test cycle. The test cycle may include activating the heater assembly, detecting a first temperature upstream of the drum at a first moment following activating the heater assembly, detecting a second temperature upstream of the drum at a second moment following the first moment, determining a temperature delta as a difference between the second temperature and the first temperature, comparing the temperature delta to a delta threshold, and initiating an alert message based on comparing the temperature delta to the delta threshold.