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The RetroZone™ 2 wire spring return damper motors are designed as drop in replacements for Honeywell’s M847D series motors on popular ZD and ARD dampers, including M847D1004, M847D1012, and many other damper actuators that use the same footprint.

Please review these specifications and dimensions carefully to ensure correct fit and function for your application.


  • Voltage: 24vac ± 10%, 60 Hz, 0.36A
  • Torque Rating: Power open 32 in. oz./spring close 32 in. oz. - torque is consistently delivered throughout the full 90º rotational operating range to open and close the damper, irrespective of whether the actuator is operating in Power Advance Mode (energized) or Spring Return Mode (de-energized)
  • Speed Stroke: Motor driven 30 sec./spring return 6 sec.
  • Rotating Angle: 93.5º
  • Noise Level: Very quiet operation, typically 40dB at 3’
  • Reliability: Statistical life reliability exceeds 120,000 cycles at 90% reliability and 100% confidence with no decay in delivery torque over the life of the actuator


CAUTION - Disconnect power supply before connecting motor wiring to prevent electrical shock or equipment damage.

  • Using a 1/8” hex wrench loosen the motor coupling from the blade shaft and remove the existing motor assembly.
  • Ensure that the damper blades are in the correct installation position:

  • Damper attached to zone control system is normally open - make sure damper is in the open position.
  • Damper attached to thermostat or switch is normally closed - make sure damper is in the closed position.
RZ3-1M stop, Adjustable stop tab with set screw, retrozone

Adjustable Stop Tab with Set Screw and installation Screw (if equipped)

Replacement Damper Motor Actuator for HONEYWELL ARD ZD M847D 2 Wire Spring Return Motor RZ3-1M and RZ3-1MBStop Installation Trouble Shooting

Damper - Open or Closed:

If the damper you are working on is attached to a zone control system, then the damper must be in the open position when the motor is tightened or attached to the damper shaft.  If the damper you are working on is connected to a thermostat or switch, then the damper must be in the closed position when the motor is tightened or attached to the damper shaft. It can be difficult to determine the open blade position of the damper in the field, since it is often not visible. On a damper connected directly to a zone control system, the damper will be typically normally open, power to close.  On a damper connected directly to a thermostat or switch, normally closed, power to open. This step requires the damper motor to not be powered. 

Normally Open Dampers: When looking at the back of the mounted motor on the damper, the blade is turned counter clockwise to close airflow, and under spring return power the blade rotates clockwise.  (If your damper is normally closed, see 4 below.)

1.  Turn the damper blade counter clockwise till the internal blade seals (most modern dampers will have blade seals)  stop the blade. Then carefully rotate the blade 90 degrees clockwise. This should be the fully open position of the damper.   Now tighten the allen screw of the motor to the damper shaft.  

2. Testing: Next tape a square of toilet tissue to a grill or register where airflow can be observed. Set thermostat serving that zone to Fan:ON.  Observe airflow. Then set Fan back to AUTO.   Go to another zone and set the Fan:ON.  This should power the subject damper motor to close of airflow:  verify your new motor is getting power with the LED light supplied with motor, or a voltage meter.

Normally Closed Dampers: You may encounter a “normally closed” damper (typically a damper connected directly to a thermostat or a switch, that is closed with no power applied, and powered to open - directly opposite of a zone control damper). In this case the mounting instructions above are reversed.  Rotate the blade clockwise till stopped, then tighten the de-energized motor to the shaft; the blade when energized with then travel counter clockwise till open.

Note that other methods of determining blade position exist if you are having issues. It can often be easy to drill a small hole in the damper to observe blade position, remove a piece of flex duct, or in some other manner actually be able to see blade position.  If you have not removed your old motor, you can try marking the shaft with a Sharpie, but the issue here is that your old motor may not fail in the fully open position due to gear train issues. 

Installation Trouble Shooting:

Failure to move upon installation is typically the result of these field issues: 


A.  Zone Control Systems - Incorrect Expectation: Users often expect all dampers to power close when wired to a zone panel, and then open when that zone’s thermostat calls, but this is incorrect. When an HVAC system is at rest, with no thermostats calling, all dampers will be open with no power. THE ONLY TIME A MOTOR RECEIVES POWER TO CLOSE is when a thermostat for SOME OTHER zone calls for heat or cool. Zones that DO NOT NEED air only then power the motors to close a damper. 


B.  Failure to Supply Power to the Motor: Related to “A” above, due to problems with zone panels, bad relays, bad thermostats, or some other issue, motor never receives power. It is best to use a voltage meter to check for 24vac. In the absence of a voltage meter, it is acceptable to take the motor only and touch the two wires directly to the 24vac transformer inputs on zone board, or to the leads of another motor known to be working. 

C.  Jammed or Broken Damper: Make sure before installing the motor, that the damper itself rotates or moves freely. 

To summarize operation of the 24vac RZ3-1 motor: looking at the back of the motor mounted on the damper, when powered the blade will move counter clockwise.   When not powered, and being reversed by spring power, the blade will move clockwise.  This is exactly the same operation as Honeywell M847D and similar motors - this motor is not turning “the wrong direction”.

But, these same directions of travel can be used for either a normally open or a normally closed damper, depending on how the damper was configured when installed. For instance, many dampers can be changed, in the field, from normally open to normally closed, by simply mounting the motor on the opposite side of a round damper.  

RZ3-1M and RZ3-1MBStop Installation

Can’t tell if your damper is open or closed?

 - please click on Technical Resources. Or see bottom of this page

    3.    Loosen the set screw on the motor collar.

    4.    Place the actuator onto the damper shaft  and insert the anti-rotation pin into the anti-rotation pin hole.

    •    If the damper shaft is a tight fit in the coupling, you can use sandpaper to smooth the damper shaft, which will allow you to fit the damper shaft into the coupler.

    5.    Double check that your damper blade and shaft are in the correct installation position for your application, then lock the collar onto the damper shaft by tightening the set screw on the collar.

    6.    Reconnect the motor wiring. Since these are AC motors, there is no polarity and either of the motor wires may be used in either position  - orange and yellow wires are provided to match the original motor wires.

ADJUSTABLE STOP TAB (if equipped):

The adjustable stop tab can be set to adjust the air flow by limiting the rotation of the blade through adjusting the rotation of the set screw attached to the damper shaft. This is used to allow air bleed in a normally open application by stopping the blade in a set position short of closing it completely. To set the adjustable blade stop:

    1.    Loosen the set screw on the adjustable stop tab.

    2.    Adjust the stop tab to the desired bleed rate.

    3.    Tighten the set screw on the adjustable stop tab.

Installation Issues?

 - please click on Technical Resources or see bottom of this page   

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