Air flow sensor kit 144501-004 for Trion Max4, Max5, and IAQ series. The kit includes the air flow sensor circuit board, wiring, and mounting hardware. The circuit board measures 2" x 1½". On the back side of this board is the thermistor that senses air flow.
Normal operation for this circuit board is to turn on the air cleaner at power up and then shut it off after 10 seconds if no air flow is sensed. If your air cleaner is turning on but then shutting off then air flow may not be reaching the sensor. Blow on the thermistor with a straw to test.
The AFS operates on 24vac that is applied to the yellow wires. When air flow is sensed, continuity will exist between the blue wires that will enable the power supply.