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Old 07-24-2020, 02:46 PM   #16
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


You can jumper and see if the fan comes on - easy test.

If a separate lower speed tap is used for continuous fan, good idea to see if the board is applying power because you can have a otherwise good blower motor with one bad speed tap.

Now, if it uses the low heat speed tap and that works okay, the board is bad for sure - would need to check sequence of operation in manual to know.

It may be a good idea to call a tech if jumpering doesn't work.
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Old 07-24-2020, 02:53 PM   #17
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


Quote:
Originally Posted by user_12345a View Post
You can jumper and see if the fan comes on - easy test.

If a separate lower speed tap is used for continuous fan, good idea to see if the board is applying power because you can have a otherwise good blower motor with one bad speed tap.

Now, if it uses the low heat speed tap and that works okay, the board is bad for sure - would need to check sequence of operation in manual to know.

It may be a good idea to call a tech if jumpering doesn't work.
Thank you

So I want to place a jumper (preferably coat/insulated wire) as shown in "orange" here?:
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Old 07-24-2020, 03:07 PM   #18
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


Yes. *
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Old 07-24-2020, 03:22 PM   #19
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Yes. *

So I just put the jumper in and tried starting the fan - no go. Does this mean the board is fried?

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Old 07-24-2020, 04:36 PM   #20
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


If the AC and the Heat both are working, doesn't that mean the blower fan itself is functioning just fine (I'm assuming both the AC and Heat are using the blower fan to distribute the cold/hot air)? If that's true, by process of logical elimination, that would seem to indicate that the circuit board is bad right?

Conversely, if the AC/heat didn't turn on at all and no air was blowing out, that would mean something's wrong with the blower or another component between the circuit board and blower right?
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Old 07-25-2020, 09:06 AM   #21
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


Your board is most likely bad.

If continuous fan uses a separate tap, there's a chance that speed tap on the motor is bad. I don't have info on this unit, so couldn't tell you.

Is this problem new or has it always been there?
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Old 07-25-2020, 09:35 AM   #22
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Originally Posted by user_12345a View Post
Your board is most likely bad.

If continuous fan uses a separate tap, there's a chance that speed tap on the motor is bad. I don't have info on this unit, so couldn't tell you.

Is this problem new or has it always been there?
The problem started within the past few months probably... it was working fine for a long period of time before this. I guess I could open up the access to the fan and try to get some pics. I ended up ordering a new control board though - hopefully that's the issue!
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Old 07-25-2020, 09:52 AM   #23
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


Change the capacitor on the blower. It's cheap and easy. Symptoms fit, although we can't be sure without testing it or changing it.

Cheers!
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Old 07-25-2020, 09:54 AM   #24
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Change the capacitor on the blower. It's cheap and easy. Symptoms fit, although we can't be sure without testing it or changing it.

Cheers!
Thanks for the suggestion. If the capacitor were bad, wouldn't the fan not turn on at all when I turn on the heat or cool air? It's strange because if I turn either of those on, the hot or cold air will blow out of the vents. It's only when I try to turn the fan on itself that nothing happens.
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Old 07-25-2020, 11:39 AM   #25
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Originally Posted by jplee3 View Post
Thanks for the suggestion. If the capacitor were bad, wouldn't the fan not turn on at all when I turn on the heat or cool air? It's strange because if I turn either of those on, the hot or cold air will blow out of the vents. It's only when I try to turn the fan on itself that nothing happens.
When the capacitor is under its rating, the motor torque is lower. It has trouble starting and will run at reduced speed. At the lower speed it may not start at all. It'll also overheat and randomly stop.

Cheers!
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Old 07-25-2020, 11:47 AM   #26
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Originally Posted by supers05 View Post
When the capacitor is under its rating, the motor torque is lower. It has trouble starting and will run at reduced speed. At the lower speed it may not start at all. It'll also overheat and randomly stop.

Cheers!


Ah ok. When I turn the heat and cool air on, it seems to blow pretty strong as it has in the past. It seems like if something were wrong, based on what you're saying, it would likely not be blowing as strong as it should be. In the past, when I would turn only the fan on, it would blow pretty strong as well. Now it just doesn't turn on at all. As far as the heat and cool air is concerned, neither seem to have randomly turned off on me to date.
I should note that I observed and issue where I turned the furnace heat on the other day, and could not get the darned thing to turn off via the Ecobee and ultimately had to hit the breaker to shut it down to stop the fan. I would think this further points to something on the control board being burnt out where, if I was trying to send a 'cancel/stop' and it didn't process, that would likely be at the control board level.

Anyway, *crossing fingers* on the replacement control board. I'm assuming it should be a pretty straightforward swap where I just plug the wires in 1 to 1 hopefully?
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Old 07-25-2020, 12:38 PM   #27
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


What is the complete model number of the furnace?

As stated before, there may be a dedicated connection for continuous fan energized with a G call. It's less likely on a 2-stage furnace like yours given low heat already uses a low speed.

I see something like that in one of the pics, can't tell if there's a connector on it or not or it's just a unused spot on the pcb.

Personally i would not change a board without verifying it's bad for sure.

Quote:
I'm assuming it should be a pretty straightforward swap where I just plug the wires in 1 to 1 hopefully?
Sometimes dip switch settings need changing.
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Old 07-25-2020, 12:43 PM   #28
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Originally Posted by user_12345a View Post
What is the complete model number of the furnace?

As stated before, there may be a dedicated connection for continuous fan energized with a G call. It's less likely on a 2-stage furnace like yours given low heat already uses a low speed.

I see something like that in one of the pics, can't tell if there's a connector on it or not or it's just a unused spot on the pcb.

Personally i would not change a board without verifying it's bad for sure.



Sometimes dip switch settings need changing.


TUD080R936K5 is the model number. Ag, I ordered the control board but suppose I could always try to cancel it if need be (they told me it would ship Mon so seems like there could be time).

BTW: you mention 2-stage - I noticed on my Ecobee a "1-stage" setting for the Furnace and then the same for the AC. I believe the Ecobee is supposed to recognize/detect whether it's a 2-stage vs 1-stage automagically, so not sure if that was the correct setting or not. All I know though is that the fan definitely was blowing prior and seems to have stopped functioning in the past few months as mentioned before.

I just read up a bit more on 2-stage vs 1-stage and see the points about the variable motor. However, it looks like my furnace/stat aren't setup or provisioned to utilize the 2-stage component...? Looking at my control board pics, the W2 terminal (which appears is intended for the 2-stage) isn't even connected. I wonder if the original owner/installer felt the 2nd stage wasn't really necessary in our area (Southern California - so it's pretty warm/moderate all year long... the coldest it gets is maybe into the 30s-40s lol)

Last edited by jplee3; 07-25-2020 at 01:03 PM.
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Old 07-25-2020, 01:05 PM   #29
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


Your furnace is a 2-stage but set for the board to do the staging, not the stat. It has a multi-speed blower, not variable.

Can't find specific info for exact unit, TUD models don't seem to have a separate circ/continuous fan connection, trane doesn't seem to say what it does in continuous mode either.

Most likely just uses the low heat speed in continuous fan mode.

Can you post a clear pic head on of where the fan wires connect to the board?
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Last edited by user_12345a; 07-25-2020 at 01:14 PM.
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Old 07-25-2020, 01:15 PM   #30
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Re: Trane XL80/Ecobee AC seems OK but Furnace/Fan control not working?


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Originally Posted by user_12345a View Post
Your furnace is a 2-stage but set for the board to do the staging, not the stat. It has a multi-speed blower, not variable.

Can't find specific info for exact unit, TUD models don't seem to have a separate circ/continuous fan connection, trane doesn't seem to say what it does in continuous mode either.

Most likely just uses the low heat speed in continuous fan mode.

Can you post a clear pic head on of where the fan wires connect to the board?
Oh I see. Most of this is above my head at this point lol.

Is this what you're looking for?


All pics I've taken so far are here:
https://photos.app.goo.gl/4pS8TEpxATeZ19W59

EDIT: I noticed there are two "CIRC" tabs - one under Neutral and another (which actually doesn't have a tab at all but just a space for one) under HOT. Does that have anything to do with this?

Last edited by jplee3; 07-25-2020 at 01:21 PM.
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