VAV Box noise

[Deans]

Just took over an account with a Trane VAV box with either a harmonic or flapping noise. the issue is this noise only happens on a Monday at 4:15 pm..
Last contractor replaced the actuator and damper seal. I am thinking it is a TOD issue with the BMS system. Owner has no prints and no sequence of operation. Where do I start?

[maxster]

one VAV box on one rooftop? do you have static control IGV or VFD?

[git-r-dun]

Oversized vav box with too low of minimum cfm setpoint. Damper barely cracks open and with 1.5'' of air on the other side of it, an orchestra breaks out. Just an idea.

[brewidus]

Might it be going through calibration at 4:15 on mondays? I've seen problems with JCI box controllers tripping out a smaller air handler on high static when the boxes closed for calibration during system operation.