# Possible bad damper motor?



## josephc618 (Nov 19, 2017)

Hi everyone. I am not an expert, I'm just a diy'er learning as I go. I have a two zone heating only system with two separate thermostats. Every time when I call for heat in zone 1, zone 2 also heats up and vice versa, but zone 2 vent outlets in the bedrooms heat does not blow as hard as the zone 1 even though zone 2 are much closer to the furnace. I suspect the damper motors are bad, when I call for heat either zones the motors does not make any noise to open it up or closes it... the weighted static pressure would swing up when heat are being called. What do you guys think? If it's bad, which types of damper motor would I need to buy to replace them? How do I know if if my damper motor a normally open or closed? Attached photos shows what the inside back plate of the damper motor says. Thank you so much.


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## user_12345a (Nov 23, 2014)

It sounds like your system is set up so dampers are naturally open and power gets applied to the dampers that need to be closed.

Start with a multi-meter and with one zone on only, check the damper connections for 24v ac and see if the zoning panel is passing power to the appropriate dampers.

Do it with both zones and post back.


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## user_12345a (Nov 23, 2014)

Got your PM.

To clarify here, the testing can be done at the zoning panel first.

Get a multi-meter that can read AC volts. (most will do resistance, dc volts and more as well)

With one zone on, set it to read AC volts, above 24v.

The meters have different thresholds and need to be set above the expected voltage.

Touch one lead to each metal connection on the part of the zoning board labelled "zone 1 damper", then do the same for "zone 2 damper".

You should get roughly 24v ac, in most cases on the damper connection for the one that's supposed to be closed.

Once you know that the zoning board is sending power and the problem isn't there, post back, there are a couple other things to be checked.


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## josephc618 (Nov 19, 2017)

Hi,
I tried testing out the voltage to both zone dampers separately. Set the multimeter to VAC and turn dial to 200 and 600 (those were the only choices). Results are at 1.8 and 23 respectively. And when power is off is says 19. Does that mean there's power going to the zone dampers and the dampers are bad because there seems to be no movement or sound from damper motors. Anything else I need to check?Here are the pics of the readings. Thanks


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## user_12345a (Nov 23, 2014)

Which terminals are connected to wires on the damper sections? I want to see if the dampers are normally closed type or open. they're probably normally open and are energized to close for the zone that doesn't need heat while the system is running.

200v ac is correct setting.

With your leads not touching anything, what does the meter read?

the 1.8v doesn't sound right.

With power off, does that mean no power to the zone panel?

The panel will have a separate transformer from the furnace or air handler. It may be plugged into a wall or take line voltage from the indoor unit.


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## josephc618 (Nov 19, 2017)

When leads not touching anything the reading says 3.2 and 48 with dial turned to 200 and 600 respectively. 
Power off means turning off thermostats but the zone board still on powered by transformer in furnace. 
According to damper wire connection to zone board, I wouldn't be able to tell if it's normally open or normally closed.

Here are some pics.


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## user_12345a (Nov 23, 2014)

Your meter is faulty or has a dying battery, it should be reading around zero on ac volts with the leads not touching anything.

Your dampers are normally spring open and close when power is applied. I can tell based on which terminals are connected and the manual.

So when zone 1 only is asking for heating, there should be 24v between M1 and M6 on zone 2 damper connection.

When zone 2 only is asking for heat, there should be 23v between M6 and M2 on zone 1 damper connection.

With power applied to the damper motor, it should move to the closed position.

If you take off the grey metal damper covers there may be a pointer or something indicating the position.


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## josephc618 (Nov 19, 2017)

user_1234a, you are correct I do have a faulty meter. I borrowed my neighbor's and it is getting the voltage that you described. Power on zone 1 gives me 24v on zone 2 damper and powering on zone 2 gives me 24v in zone 1 damper. So I'm guessing it's a damper issue. I also pulled the metal casing off the damper motor and steers at the motor and I do not see or hear any movements. Could it be possibly two bad dampers? There used to be yellow (fan) wire connect to Y therminal on both thermostat zones, I removed them because I don't think I will be using the fan. Do I need to keep those wires in place to maybe make the damper work?


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## user_12345a (Nov 23, 2014)

Is is that one damper isn't working or both?

Did anything change when this problem started?

Do you have a bypass duct directly to return or is the air dumped somewhere else?

---
So you know the zone panel is working okay.

Maybe disconnect one at a time and check the resistance to see if the circuit is complete.

I would check resistance directly at the damper motor too with the wires disconnected there.

Do you feel a bit of a spring when you try to move them by hand or is it lose? i believe the spring is supposed to hold the damper open and it closes when power is applied.

it's set up this way to if something fails, the dampers fail open rather than closed so you don't damage your furnace.


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## josephc618 (Nov 19, 2017)

Well I tried using zone 2 a year ago and it never worked, thought it was thermostat but it's not because I swapped out the thermostat and it still didn't turn on. Then I swapped out the zone board and reconnected the wires back to the same terminals and then zone 2 started working, but it appears to be working just like zone 1. 

Yes both dampers doesn't seems to be working, no noise, no movement (see pic 1)

There is a bypass duct (see pic 2) to the left with a weight on it.

Just now I found an arrow lever behind the damper motor (see pic 3). I manually closed zone 1 damper motor and zone 2 heat started to blow much harder warm air.


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## user_12345a (Nov 23, 2014)

did you change the type of zone board? did you go through installation manual and set it up for your application?

See if the dampers are getting 24v direct.

if they are and not moving, disconnect and ohm out damper motors.


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## josephc618 (Nov 19, 2017)

I used to have a Honeywell mastertrol mini zone and they no longer sells replacement, so I purchased the Honeywell hz311 and follow the diagrams / installation instructions of both zone boards and connected wire-by-wire. I just didn't connect the yellow fan wires to both zone because I don't think I would ever use the fan. But if it needs to be connected in order for the damper motor to work then I will reconnect it.

The damper isn't moving. What do you mean by disconnect and ohm out damper motors?


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## user_12345a (Nov 23, 2014)

The wire going to the damper would likely be wire-nutted to the damper's leads. if not, the damper has screw connections.

If you disconnect the damper and check resistance across the damper motor, can see if the winding is open or there's another issue.

Assuming the dampers are getting power from zone panel and there's no problem like broken wire or bad connection, if they aren't opening with power applied, they're bad.

The yellow fan wire? what's that? Are you talking about the G connection on the t-stat?

Did it ever work right after changing the panel?

What are the model numbers of the dampers?


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## beenthere (Oct 11, 2008)

Those zone damper motors are still available, and easy to change out. Not an uncommon thing for them to wear out.

Make sure you are getting 24 volts to the damper motor. So that you know its not just a broken wire.

The yellow wire from the thermostat should be for A/C, not for fan on control.


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## josephc618 (Nov 19, 2017)

beenthere: you're right, the yellow wire is for ac, I got it mixed up in my head, I detached it because I don't have AC. 

I've check the power going into the damper with a multimeter, there's definitely power going through it. I am not sure what model is my damper, all I can find around damper is an order sticker from Honeywell (see pic). If anyone can let me know what model it is or a replacement please let me know. Thanks


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## beenthere (Oct 11, 2008)

Should be this one.

https://www.amazon.com/Honeywell-802360JA-Replacement-Motor-Valves/dp/B0006UPLQC


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## josephc618 (Nov 19, 2017)

Thank you so much. Will order it and give it a try, will post back with outcome. Thanks beenthere and user12345a for all your help


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