# Trane XL90 - Blower runs but no heat



## dchanson (Apr 17, 2012)

Hello,
I'm a new home owner (bought this house in September) and I woke up this morning to a cold house. I checked the thermostat and it read about 65 (I had the temp set to 74). I turned the heat up a couple notches and left for work. When I got home, it still hadn't warmed up at all (at least not any more than the warmer daytime temps would've caused). 
I'm not even sure where to begin troubleshooting. I've heard the first thing everyone asks for is the error flash codes. This particular model will show the last four faults on power up. They are as follows:
2 -- System Lockout (Retries or Recycles exceeded)
8 -- Low flame sense
2 -- System Lockout (Retries or Recycles exceeded)
2 -- System Lockout (Retries or Recycles exceeded)
The paperwork I have states that this was a new install in 2005.
I'm not really sure what to do next, but any assistance is greatly appreciated!!


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Hello,
> I'm a new home owner (bought this house in September) and I woke up this morning to a cold house. I checked the thermostat and it read about 65 (I had the temp set to 74). I turned the heat up a couple notches and left for work. When I got home, it still hadn't warmed up at all (at least not any more than the warmer daytime temps would've caused).
> I'm not even sure where to begin troubleshooting. I've heard the first thing everyone asks for is the error flash codes. This particular model will show the last four faults on power up. They are as follows:
> 2 -- System Lockout (Retries or Recycles exceeded)
> ...


 what i would would do is power the unit down at switch ...set to heat and power back up.. observe what happens at furnace.....start from there:yes:


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## how (Feb 26, 2011)

Next power down furnace, clean flame sensor with steel wool, power it back up and see what happens.


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## dchanson (Apr 17, 2012)

Ben:
When I turn it off, set it to heat, nothing happens. If I flip it on, it starts to try to heat, and it sounds like something tries to start and then 'gives up' after a couple of seconds (you can hear a kind of 'squeak' when it does). Then the blower will turn on and run (no heat) for a short period of time and quit. I have a video uploading so you can hear it and see what I'm talking about, but it looks like it could be about a half hour before it's done uploading (slow internet). Do you agree with advice to clean flame sensor with steel wool (not that I don't trust you, How, just always nice to have a second opinion :thumbup: )?

How: 
Where is this sensor located, and do you recommend any other precautionary measures prior to accessing/cleaning it?

Thanks again guys!!!


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## how (Feb 26, 2011)

If the flame came on for a few seconds and then turned off, then the flame sensor would be the most common culprit. Do you have an inspection port into the burners to see?
If it didn't even ignite, then *no* its not a flame sensor problem.


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Ben:
> When I turn it off, set it to heat, nothing happens. If I flip it on, it starts to try to heat, and it sounds like something tries to start and then 'gives up' after a couple of seconds (you can hear a kind of 'squeak' when it does). Then the blower will turn on and run (no heat) for a short period of time and quit. I have a video uploading so you can hear it and see what I'm talking about, but it looks like it could be about a half hour before it's done uploading (slow internet). Do you agree with advice to clean flame sensor with steel wool (not that I don't trust you, How, just always nice to have a second opinion :thumbup: )?
> 
> How:
> ...


 yes flame sensor could be cleaned...but if you hear a squeal at start up it sounds like inducer motor....this starts up first to set ignition sequence....


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## dchanson (Apr 17, 2012)

How: I'm not sure where an inspection port would be other than the one to check the indicator lights, I haven't taken any panels off yet, but I could certainly do that if need be. 


Ben: It's more of a squeak than a squeal. I know that sounds like tomato tomahto, but it sounds more like air pressure being let out of a tight opening than the squeal of something mechanical...if that makes sense. You can hear it really well in the video.

I'm going to see if I can identify the flame sensor. Back in a minute.


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> How: I'm not sure where an inspection port would be other than the one to check the indicator lights, I haven't taken any panels off yet, but I could certainly do that if need be.
> 
> 
> Ben: It's more of a squeak than a squeal. I know that sounds like tomato tomahto, but it sounds more like air pressure being let out of a tight opening than the squeal of something mechanical...if that makes sense. You can hear it really well in the video.
> ...


 at this point I don't think its the flame sensor...that squeak is still the draft inducer motor...you can remove upper door panel..


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## dchanson (Apr 17, 2012)

Okay. Found the stuff we were looking for. The thing I mentioned that sounds like it 'tries to fire up' at first is a small black motor on the lower right side of the upper portion of the furnace (video uploading). The flame DOES light for a second or two, but is then extinguished (the 'squeak' happens at the exact same time the flame is extinguished, I'm certain the two are somehow related).


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Okay. Found the stuff we were looking for. The thing I mentioned that sounds like it 'tries to fire up' at first is a small black motor on the lower right side of the upper portion of the furnace (video uploading). The flame DOES light for a second or two, but is then extinguished (the 'squeak' happens at the exact same time the flame is extinguished, I'm certain the two are somehow related).


 ok now were getting somwhere... may need to see and hear video.....


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## dchanson (Apr 17, 2012)

Video #1 - http://youtu.be/jl9SRxHPGjE
This just gives a general idea of what it's doing, and 'the sound'

There is another video currently uploading (about 10 minutes out) that shows the flame lighting and some of the other 'internalities' of the furnace when it's trying to fire. It also shows the small black motor I referred to.

Link will be posted as soon as upload is complete.


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Video #1 - http://youtu.be/jl9SRxHPGjE
> This just gives a general idea of what it's doing, and 'the sound'
> 
> There is another video currently uploading (about 10 minutes out) that shows the flame lighting and some of the other 'internalities' of the furnace when it's trying to fire. It also shows the small black motor I referred to.
> ...


 did you take off the upper door panel....


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## dchanson (Apr 17, 2012)

I do in video #2


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## dchanson (Apr 17, 2012)

Video 2: http://youtu.be/i4EGf45JFyY


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Video 2: http://youtu.be/i4EGf45JFyY


 Iam going to say you should check exhaust pipe for blockage or intake for blockage ..


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## dchanson (Apr 17, 2012)

Where exactly would these be located, and do I have to turn off the gas or anything before working on them?


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> Where exactly would these be located, and do I have to turn off the gas or anything before working on them?


 these are the white pvc pipes on top of furnace that go to outside...you could start furnace and go outside to see if it has a strong exhaust... for the intake i think you could remove burnner cover ..thats where little port window is... fire up furnace see if it stays running....


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## dchanson (Apr 17, 2012)

I'll give it a shot. Thanks for the advice!


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> I'll give it a shot. Thanks for the advice!


 look inside pipe if you can see if something is in there....nest ,bees, wasps.. doesen't take much to shut down furnace... the pipe hooked to little black blower is exhaust....other is intake...


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> I'll give it a shot. Thanks for the advice!


 hey guy i have to run out will be back in 1/2 hr or hour sorry..hang tight others will help as well....ben....


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## dchanson (Apr 17, 2012)

Just checked it out. If I turn it on and go outside, the exhaust is blowing strong enough to shoot a leaf off of my hand fro about 6" in front of it, and the intake had enough suction to hold a leaf to it until the blower shut off. After a few 'attempts' at firing up and dying after a couple seconds, it eventually started and stayed going for about a minute or so. I went downstairs to check, and it was running but there was no fire. Thoughts?


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## dchanson (Apr 17, 2012)

Take your time. I REALLY appreciate all the help!


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## how (Feb 26, 2011)

Given the fault codes for the furnace, the easiest and most likely cause will be a dirty flame sensor. ( eg. flame lock out instead of pressure switch). When the sensor gets dirty (and they all do) when burners ignites, the flame sensor does not read the flame burning properly and it immediately shuts down the gas for a while. A lock out code will start flashing after a number of aborted attempts at ignition. 

The thing that you are seeing inside the burner compartment that is glowing is the igniter. Beside the burner that is furthest away from the igniter, is the flame sensor. It looks like a short piece of coathanger wire thats imbedded in a porcelon holder.

Sensor cleaning instructions...
Power to the furnace gets turned off. The burner door gets unscrewed & removed. The sheet metal screw holding the flame sensor gets undone.
Remove flame sensor and scub the wire clean with steel wool. Reverse previous steps and tell us what happens.
This may not be the cause but it is the most reasonable 1st step.


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## dchanson (Apr 17, 2012)

I got the cover off and found the piece you are referring to, but I need a different bit driver to remove it for cleaning (it does look pretty dirty). The local shop is closed so I'll have to get to it tomorrow. Thanks again for the help, I'll update tomorrow!


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## ben's plumbing (Oct 6, 2011)

dchanson said:


> I got the cover off and found the piece you are referring to, but I need a different bit driver to remove it for cleaning (it does look pretty dirty). The local shop is closed so I'll have to get to it tomorrow. Thanks again for the help, I'll update tomorrow!


 again sorry for leaving yes clean flame sensor...if furnace ran for a few minitues then shut down most likely flame sensor....


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## how (Feb 26, 2011)

Sometimes with nimble figers and a bit of patience you can clean the flame sensor rod without removing it.


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## dchanson (Apr 17, 2012)

how said:


> Sometimes with nimble figers and a bit of patience you can clean the flame sensor rod without removing it.


I thought about that, but this just gives me an excuse to buy a few more tools :thumbsup:
Plus, I always sleep a little better when my girlfriend is cold 

Thanks again you guys, I'll let you know what comes of it tomorrow!


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## how (Feb 26, 2011)

I never considered the advantages of an intermitantly operating furnace. Kind of blows a hole in my regular furnace maintenance speech.


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## dchanson (Apr 17, 2012)

That did it!! Thanks a million for the help you two! One more DIY project under the belt :thumbup:


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