# replacing Honeywell damper motor



## piconut (5 mo ago)

First off I just want to say that I am a retired high school teacher and homeowner and I’m not an HVAC technician (although I'm mechanically inclined). Here is my issue: I have two of four Honeywell damper motors (M847D-Zone) which are intermittently working (not opening properly when called by the Lennox zone control board). When they are supposed to be open and allowing air to flow, if I tap on the top of the motor I can get it to work and open up. Sometimes it will work for several days to a week before it gets stuck closed again. I purchased an identical replacement Honeywell damper motor but I am not sure exactly how to replace it or what position the motor and damper need to be in before I loosen the set screw. If I understand correctly, this motor is set up for spring open and power closed. So do I turn off the whole HVAC first, thereby cutting power to the damper so that it will spring open, then disconnect the wires, unscrew the set screw, and lift it off the duct? Since the insulation around the duct is sealed with mastic, I cannot look into the duct to know what state (open or closed) the actual damper is in. I do not want to have to cut into the duct to see the damper position. Also, the set pin on the bottom side of the damper motor appears to be threaded on the inside and so I assume that is for a screw so that the motor can be secured from the inside of the duct. Is this correct?

It looks like a fairly straight forward swap of damper motors, but I just want to make sure I’m not overlooking some detail that could cause me problems. Thank you for your help.


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