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Old 02-08-2011, 05:55 PM   #1
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Trane XL80 gas furnace goes into lockout


Hello all,

I am having a problem with a Trane XL80 furnace that goes into lockout mode. The control box is not one of the newer models that flash the various troubleshooting codes. When it goes into lockout, it simply flashes twice and a pause then flash twice.

Now, here is the mystery. This only occurs when the front panel cover is installed on the unit. If I leave the panel off, it works fine. But if I put the front cover on it, sometime in the next 48 hours it will go into lockout mode. If I leave the cover off, it works great.

The induced draft motor works fine, as well as, the negative pressure switch. The settings on the limit switch are set to factory.

Does anyone have any ideas / troubleshooting suggestions ?

Larry W.

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Old 02-08-2011, 06:27 PM   #2
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Trane XL80 gas furnace goes into lockout


Sounds like it's not getting enough combustion air to burn. Does the panel have lovers & are they clear as in not stopped up ? The flashing twice then pausing should be the code. Look on the blower door panel & see what is list for 2 flashes

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Old 02-08-2011, 07:00 PM   #3
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Trane XL80 gas furnace goes into lockout


The panel has vent openings that are clear and open. I have even left the door open to the furnace room to allow more air but doesn't make any difference.

The code for two flashes is simply "system lockout - retries exceeded."

Larry W
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Old 02-09-2011, 11:08 AM   #4
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Trane XL80 gas furnace goes into lockout


Filter clean? Try temporarily with no filter, cover panel on.

Maybe clean flame sensor/thermocouple. If dirty, maybe needs more air? Can't hurt to check.

http://www.youtube.com/watch?v=I86jo...eature=related
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Old 02-22-2011, 09:58 PM   #5
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Trane XL80 gas furnace goes into lockout


I still don't have a solution to this problem but I have one idea to try.

It could be that the problem lies in some restriction in the air supply lines and causing the unit to get hotter than it should under normal operation
and thus causing the unit to go into lockout mode.

So, I have unhooked part of the supply line ducting to allow more free flow and replaced the front panel to see if the problem occurs again.

I'll update the forum with the results.

thanks to all for suggestions

Larry W
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Old 02-23-2011, 01:40 AM   #6
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Trane XL80 gas furnace goes into lockout


Quote:
Originally Posted by Larry W View Post
I still don't have a solution to this problem but I have one idea to try.

It could be that the problem lies in some restriction in the air supply lines and causing the unit to get hotter than it should under normal operation
and thus causing the unit to go into lockout mode.

So, I have unhooked part of the supply line ducting to allow more free flow and replaced the front panel to see if the problem occurs again.

I'll update the forum with the results.

thanks to all for suggestions

Larry W
The cover you take off to run the furnace is the one that covers the blower right? More than likely a return air issue, by taking the panel off your essentially opening up the return system. Check all your returns, maybe somethings obstructing them. Lack of return air can also cause high limit. How long has this furnace been installed? Did you install it? Was this furnace and the duct system installed at the same time?
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Old 02-23-2011, 06:18 AM   #7
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Trane XL80 gas furnace goes into lockout


lock out is a retry problem meaning ignition problem.... Clean the flame sensor
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Old 02-26-2011, 02:02 PM   #8
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Trane XL80 gas furnace goes into lockout


The front panel that I removed only covers the components of the furnace. It doesn't change air flow of the exchanger. It simply covers the various electrical components ( limit switch, electronic control module, and gas lines and valve).

I disconnected one of the supply lines and replaced the cover. The unit ran for 24 hours with no lockout.

I replaced the cover and reconnected the supply line. During the next 24 hours, the unit went into lockout.

So, I proceeded to check the supply duct system. After crawling around in the crawl space for about 20 minutes, I found that one of the main supply ducts had been crushed and was not allowing any air flow.

So, I am now pretty well convinced that this is the problem.

When I get the duct system repaired, I 'll post an update.

thanks to all for the suggestions.

Larry W.
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Old 02-26-2011, 02:03 PM   #9
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Trane XL80 gas furnace goes into lockout


lock out is a retry problem meaning ignition problem.... Clean the flame sensor

If you are not going to listen to our help then we wont continue to give it to you.
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Old 02-26-2011, 06:43 PM   #10
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Trane XL80 gas furnace goes into lockout


I have cleaned the flame sensor. And checked all of the electrical connections and treated them with Noalox. None of which corrected the problem.

Larry W.
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Old 02-26-2011, 08:43 PM   #11
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Trane XL80 gas furnace goes into lockout


Depending on the size of the obstructed supply it could be the problem, still doesn't make sense about the front panel though...
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Old 02-26-2011, 10:27 PM   #12
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Trane XL80 gas furnace goes into lockout


are you sure you got the diag code correct? A lock out has to do with ignition, not air flow. I'm confused! Does the system light everytime? please post the events that happen during a call for heat.
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Old 02-28-2011, 04:20 PM   #13
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Trane XL80 gas furnace goes into lockout


The thermostat calls for heat.

The induced draft motor starts and runs.

About 20-30 seconds after induced draft motor starts, the hot
ignition plate begins to glow.

About 10 seconds after the hot igniter starts to glow the gas comes
on and ignites.

After about 1-3 minutes, the fan motor begins to run and delivers heat through the duct system.

The furnace will go into lockout sometime in the next 24 hours.

If I remove the front panel that covers the various components, the furnace will operate just fine.

If I leave the panel on and disconnect some of the supply ducting, the furnace will operate just fine. I found a supply duct that had been crushed. I bought this house about 4 months ago and have no idea how the duct got crushed.

One possibility might be that the induced draft motor gets to hot and does not come on and causing the lockout. I think it is thermally protected.

Obviously, there is something getting hot and causing the lockout.

The panel that I am referring to does not cover any of the ducting/fan motor air flow. It is simply a panel that covers the induced draft motor, electronic control module, limit switch module, gas valve, gas lines, etc.

I have cleaned the flame sensor and the filters are new.
Larry W.
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Old 02-28-2011, 05:17 PM   #14
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Trane XL80 gas furnace goes into lockout


You are saying you have not observed the furnace fault...... If it were the inducer not starting it would be a pressure switch code. Have you removed the burners and cleaned the face and crossovers? Dirty crossovers can keep all the burners from igniting and there by sending the furnace into lockout after a few attempts and not seeing a flame signal.
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Old 02-28-2011, 05:52 PM   #15
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Trane XL80 gas furnace goes into lockout


I have not observed the problem first hand.

I have been working on the house and only see that the furnace has either gone into lockout or is running when I return.

This is when I discovered that if the panel was left off the furnace would operate just fine, but if I installed the panel and returned 24 hours later, the unit would be in lockout mode.

The negative pressure switch seems to work okay. I unplugged the hose going to the switch and the furnace flame immediately shut down.
Reconnected the hose and the unit works fine.

The control is an older model that is ignition only control. The control flashes which means that the unit has gone into lockout. The only other code is red light on continuously ndicating that the control is faulty.

I have not cleaned the burners or crossover. When I had the gas turned on, the service man looked at the burners and told me that they looked good. Almost all blue flame on each set of burners.

Larry W

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