Loose damper in duct maybe?

[Jreidy]

Could damper be loose inside duct? How do I fix that? I have a 2 zone EWC system with ma-nd3 damper motors. The downstairs zone 1 seems to work fine but upstairs zone 2 is way hotter than I want. It's getting heat when the heat is off upstairs. The damper lights indicate correctly what should be going on, but something isn't right. How can I see if the damper blade fell off? Furnace guy came and charged me $80 to tell me system is working properly, but clearly it is not.

[Jreidy]

I removed the upstairs damper from the ductwork to inspect it. It is working properly. So why am I getting heat upstairs when thermostat is off and damper is closed?

[Paul Z.]

Remove damper from duct work when it should be closed, then check and see that all blade are working correctly. While it is out check damper complete operation, (open and close). Make sure damper is the correct size for the duct, measure duct inside and damper.