Retrozone&Flexdamper are trademarks of Retrozone Inc.

 Free Standard Shipping on Orders $25+ Continental USA only

  Shipping to Alaska, Hawaii, and International shipping to Canada extra. Please place the order and factory will advise of additional shipping amounts prior to shipping. 

Credit Cards will not be charged until shipping amounts are verified. 


Expedited shipping available. Please call for pricing. 

Replacing Obsolete Damper Motors

 1. Finding or replacing obsolete damper motors? Send us some pictures: 

Cant find a replacement motor?  RetroZone inc. is the leader in replacing damper motors, even obsolete motors that can’t be found.  We manufacture a wide range of adapters and parts to adapt current motors-often far better than the original motors-to damper applications.

  • If its a “Synchron” branded number, we need the 5 digit number ending in R or L usually printed on the band around the motor near where the wires come out

  • If we ask for pictures, its best if you can remove the motor, and take a picture of the bottom of the motor, as well as where the motor was removed from the device; We may need to see what motor kit will work.  Don’t get too close, we need a field of view of about a foot where we can see how much space is available for a possibly larger motor. 

  • On obsolete motors, its more important for us to see the device or damper shaft  and surrounding area once the motor is removed, so we can evaluate what kit to use, or what special kit to put together.  Any dimensions of the shaft or parts present for us to attach to may be useful. 

  • ”Motor” on most dampers means the entire motor assembly (with gears and springs)as it is removed from the damper drive shaft.  Motors part of an motor assembly are typically not replaceable. 

  • Dampers used to control combustion gasses from gas appliances are considered “life safety” and will usually have extra wires for an end switch, you may need to replace the entire device with a UL or other agency certified damper.


Please send your photos to support@retrozone.com

2. Replacing the entire damper instead of just the motor:

  • Dampers in rectangular ducts are typically easy to change by removing a few screws in the mounting place, and sliding the damper out. This may be a better option with very old dampers.  We can help you decide what dampers are best suited for replacement as an option to replacing just the motor. 

  • Dampers in Round Flexible type “Flex-duct” can often be easily changed as an alternative to replacing just the motor, if no good motor solution exists.  Email us and we can help you decide which of our dampers is best. 

  • Dampers in rigid steel pipe can be problematic, but not impossible to change. However, a motor kit for these will often be the best solution.

3. Two wire “spring return” versus 3 wire “power open, power close” dampers:

  • 2-wire “spring return” versus 3 wire “power open, power close” dampers: Chances are you are replacing a  2-wire spring return damper motor (due to low cost) which are the most common.  However, in general these spring return motors have a far higher failure rate, for two reasons:

        (1) The motors, when energized, must pull power all the time to overcome the spring, and as a result can get very hot.

        (2) The Spring tension on the gears, especially plastic gears, often causes premature failure.

                 Despite claims, these dampers can fail in any position. 

 4. Using a three-wire power open/power close type damper to replace a two-wire “spring return” damper motor.

  • You can replace with a three-wire damper in most cases if  you already  have, or can get, a third wire from the damper motor to  the zone panel, thermostat, switch, or other control device.  This is true even if your zone panel has only a 2-wire damper output; we will tell you how to hook up the third wire.  

  • Our three-wire “power open power close” dampers only use power when moving, never get hot, and have no spring to wear and tear  on gears, so its the way to go in most applications. 

 5. Can I use a thermostat on a three wire power open/power close damper without using a relay? How does that work?

 Yes you can, all of our three-wire dampers may be used with a simple, conventional thermostat with no relay needed.  Power is wired to terminals 1 and 2 on the motor full time (but its only used when the damper is moving), and then 3 is wired to the thermostat Y or W or both. Click on slave zone diagram for more information. 

This website makes use of cookies. Please see our privacy policy for details.