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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I just purchased a house with a hvac system with a Honeywell

Customer Question

I just purchased a house with a hvac system with a Honeywell M836 damper installed above the blower. The damper moves a flap that sends air flow to either the upstairs or downstairs. The damper is controlled by a switch on the wall.
My problem is the wiring was disconnected prior to us moving in and I don't want to rewire incorrectly and fry something. The damper has red, white, blue, line 1, and line 2. It looks as if it used the 24v transformer in the main system going to the thermostat to power the damper. I can supply lots of pics but I don't know how to upload them here. I really want to get this working again. Could I buy a separate 24v transformer to just power the damper?
Submitted: 2 months ago.
Category: HVAC
Expert:  Rick replied 2 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

24 volt common goes to L2, 24 volt hot is switched with transformer hot to switch then switch to L1

Customer: replied 2 months ago.
Hi Rick, I wired per your instructions. The damper motor does turn but in one direction almost all the way like it should but struggles and hums during the last few revolutions, but when I flip the switch it springs back only about half way. Shouldn't it be powered in the opposite direction also? What are the r,w,b wires for coming from the motor? Also there is a relay underneath the unit. Is this for the damper or is it used for something else?Thanks
Customer: replied 2 months ago.
Ooh, I just realized I can upload a photo. See attached
Expert:  Rick replied 2 months ago.

Sounds like damper motor return isn't functioning properly. R, W & B are end switch wires to control another device. I have no way of knowing what the relay is for based solely on your description of where it is or the pictures.