HVAC Zone Damper help/advice

I have an HVAC system with two zones (upstairs and downstairs). It has the Honeywell power actuator to open/close the damper. The issue I face is that when the upstairs zone is operating and downstairs is 'off', I still get some airflow in the downstairs registers. This can end up making downstairs too cold.

I think I am correct in saying that the damper won't seal 100% some some airflow to the downstairs zone is expected....It just seems too much for me.

So the question I have is how to adjust the damper? It is rectangular if that matters. If I disconnect the motor from the damper rod and rotate it manually, will it be fully open at one end of the rotation, and fully closed at the other? If so, if I rotate it to the fully open or closed position and then re-attach the motor, will that help with the issue?

I have what looks like the same damper here.



Your picture doesn’t show how far the damper is closing. Poke your phone around the corner and have a look at that first.

If I’m reading it correctly, the damper can be adjusted to stop at several positions, so maybe yours just needs to be adjusted.

Exactly as stated above. Those adjustable, get a picture of where it is at the closed position. One question I have, is there a bypass damper. This will go between the supply (before dampers) and the return. If there isn’t one, that supply damper is adjusted to let the overflow of pressure bleed off into the downstairs zone.

I have the same zone control and damper motors.
On mine the issue is the damper flap /door whatever and the seal inside the housing. The seal is no longer there , so the flap has nothing to completely close off the air flow.

Kind of like a car door that has no weatherstripping .

I never set the zone dampers to close completely anyway, so I wouldn't worry about it unless it causes some other issue.
The only repair is to replace the damper. No one has replacement parts for these, other than the actuator/motor.

Good damper are opposed blade with rubber tipped blades and seals for the sides of the blades to cut down on leakage. Damper adjust with actuator in closed position don't worry about 100% open. Blade at 90% open or more is flowing 100%

A lot of systems have some feed to the 2nd zone when the 1st calls, and vice versa. Most installers design them that way. You either blow some air into the non-calling zone, or you install a bypass damper into the ductwok and it dumps back into the return. Better off dumping a small % into the zone that isn't calling. The return is pulling from the whole house either way