Why Is the VAV Box Not Responding?
If a VAV box does not respond to thermostat adjustments, the issue is typically:
- Communication failure
- Controller lockup
- Sensor malfunction
- Actuator failure
Common Causes
- BACnet or N2 communication loss
- Broken thermostat wiring
- Failed damper actuator
- Incorrect controller configuration
- Power supply failure
Troubleshooting
1. Verify Power to Controller
Measure voltage at controller terminals.
2. Check Communication Status
Confirm device is online in supervisory system.
3. Inspect Actuator Operation
Manually command damper open/close.
4. Test Thermostat Signal
Verify signal continuity and calibration.
FAQ
Can the VAV operate without communication?
Some controllers enter a fallback mode but functionality may be limited.