EWC-ST-2D Ultra-Zone Dampers Not Working

[mma_jma]

We have an EWC-ST-2D Ultra-Zone system that has 2 zones. It appears that one or both of the dampers are malfunctioning. What is the diagnostic process to determine if it is the damper or the control panel that is having problems?

The damper motors are MA-RDN. I located a number on the damper ductwork. The number was 090405A0014.

[Eric K.]

The MA-RDN motors have terminals 1, 2, & 4. To test the motor, apply 24vac to terminals 1 & 2 and the motor should close. Then bridge terminals 2 & 4 and the motor should open.

To test the panel outputs, you should measure 24vac across terminals 1&2 at all times and across terminals 1&4 when the damper is powered open.

Eric

[mma_jma]

There are no indicator lights on the damper. Is there an easy way to determine if the damper is open or closed?

[Eric K.]

Unfortunately, there is no simple way to see if the damper is opened or closed. There are two ways you can accomplish this.

1. You can disconnect one end of the damper or cut an opening in the duct to observe the operation of the damper.

2. If you turn the Fan switch on the Master Thermostat (Zone 1) to the On Position, then do the damper tests as stated in an earlier post, you can feel the airflow from the registers for the zone in question to determine if there is a change of position or not.

Eric

[mma_jma]

I finally had a chance to look inside the ductwork and watch the dampers and it appears that the damper for zone 2 is sticking. What is the best fix? It is a 14" damper unit. Do I need a complete damper unit or can I get a replacement motor? Where and how quickly can I get these items? I am located in Knoxville, TN.

[Pcyrana]

Unfortunately that motor is no longer in production. The entire damper assembly would have to be replaced. The replacement damper model would be the URD 14. Some distributors in the Knoxville area that carry our product are 1. Johnstone Supply - 865-525-6296, 2. Ferguson Enterprises - 865-691-5880, 3.Carrier MidSouth - 865-558-6336.