TinnerFlow™3rd YearVAV / ControlsYELLOW · Check First
If the actuator moves but the internal damper blade drops or disconnects, the issue may be mechanical linkage/shaft failure inside the box. Verify access, blade movement, and linkage before blaming controls.
A VAV can lose airflow when the internal damper shaft, collar, pin, or linkage slips and the blades fall shut. The actuator may still make noise or move without moving the blades.
Use existing access if possible. If access is needed, get direction before cutting. Verify blade movement by hand when safe, inspect shaft/collar linkage, reset or repair the mechanical connection, then patch/seal and have controls/TAB retest.
Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.