Damper Troubleshooting

[RA3210]

I have a EWC NCM Zone control with two zones active, zones 1 and 2. Each zone has a dedicated thermostat and a zone damper with a MA-ND3 control. I recently noticed that air flow seemed to be reduced in zone 1, and that zone 2 was receiving heated air flow even when the thermostat was not calling for heat; I also noticed a thumping sound when the system would cycle off which I took to indicate an over pressurization of the system. Fan appears to run at a uniform speed.

The LED indicators on the MA-ND3 controls seems to correctly reflect what the control panel is calling for...open when heat being called for...but I do not see movement of the damper indicator.

How can I determine why the dampers are not moving in response to zone control signals? Seems strange that both motors would fail at same time...LEDs are illuminating so there is power to unit...

[Paul Z.]

test voltage at the motor terminal block, M1-M4 open, M1-M6 closed. There should never be voltage on 4-6 at the same time, if so them motor has internal short.

[RA3210]

Thanks will try this today.