HF33 — Airflow Sensor Out of Operating Range (VS/ZVS-01 or PS Pressure Sensor)

What does HF33 mean?

This error indicates that the airflow sensor is reading a value outside its normal operating range. The specific cause can vary depending on whether a VS/ZVS-01 airflow sensor or a PS pressure sensor is installed.

• For VS or ZVS-01 sensors: Sensor reading pressure higher than 2000 counts, or incorrect calibration.
• For VS or ZVS-01 sensors: Defective field wiring or a faulty sensor.
• For PS Pressure Sensor: Excessive static or differential pressure beyond the sensor's rating (0.5 in. wg for PS-01, 2.0 in. wg for PS-02).
• For PS Pressure Sensor: Incorrect or faulty hose connections to the PSP pressure pickup, or improperly wired sensor connections to the damper actuator.

Click steps to track your progress.

1. 1

   For VS or ZVS-01 sensors, check the zone velocity sensor reading with the supply-air fan off. It should be between 00 01 and 00 10. If not, calibrate using the slave thermostat (rotary switch position 8) or Device Calibration software.

2. 2

   For VS or ZVS-01 sensors, if calibration fails, check the voltage between the white and red wires at the damper actuator. It should read 10 VDC. If not, the damper board may be defective.

3. 3

   For VS or ZVS-01 sensors, if voltage is good at the actuator, check the same voltage at the sensor. If not 10 VDC, the field wiring is defective.

4. 4

   For PS Pressure Sensors, check for excessive static or differential pressure at the sensor. Ensure it's not exceeding the maximum rated pressure for your sensor model.

5. 5

   For PS Pressure Sensors, check the hose connections from the PSP pressure pickup to the PS sensor for correctness and integrity.

6. 6

   For PS Pressure Sensors, verify that the wiring from the sensor to the damper actuator is complete and well-connected. Ensure 'O' connections are not used or shorted to ground.