Trane xe90 Blower is running all the time

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skeatus

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The blower on my Trane xe90 is always running I set the the thermostat to off and it still runs. The only way I can get it to turn off is to shut the furnance off at the shutoff. I just replaced the circuit board just over a year ago. I read other forums and they say the the fan relay. I think that is integrated in my circuit board, but I am not sure. Please let me know where to go next.
 

kok328

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Could be the thermostat is bad, thermostat wires are shorted or blower relay is stuck closed.
To narrow down the problem, disconnect the red thermostat wire inside the furnace and then turn the furnace back on w/the cover panels reinstalled.
If the blower comes on then the problem will be the blower relay.
 

skeatus

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Removed red wireand blower did not come on. Does that mean my themostat?
 

hvactechfw

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It means your stat or your wiring. Next step reinstall red wire to control board, then remove green wire from stat. Does blower shut off? If so then stat, if not then wiring is shorted.
 

skeatus

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Ok took off green wire from stat and blower still ran. Where do i start to try and find short. I have wires coming from every where.
 

kok328

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Looks like the thermostat wires may be shorted (red is touch green).
To confirm this disconnect both the green and red wire from each end (thermostat and furnace) and then check for continuity between them.
If continuity is present then you have a short. If not continuity then I'm not sure what the problem is.
 

kok328

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run it by "paul52446m", he's up in Houghton Lake.

How did you determine that the stat wires are not crossed ?
 

skeatus

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I removed the stat from the furnance and the blower still ran
 

kok328

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When you removed the red stat wire from inside the furnace, you reported back that the blower did not come on.
When you disconnected the green wire from the stat, you reported that the blower did come on and stayed on.
You have not performed a continuity test on the red & green wires to determine if the wires are shorted together.
I think you'll find that you do have continuity between the red and green stat wires.
Disconnect the red & green stat wires from inside the furnace and from the stat and perform a continuity test with a meter.
Otherwise, hook the stat up to the furnace using a few feet of new stat wire and you'll find that your problem goes away. In which case all you need to do is replace your existing stat wires.
 

helios

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I have a similar problem with a Luxaire unit. I came home one evening and found the blower running even though the stat was off. I had to shut the power off to stop it any suggestions on this one? The blower motor is free and no unusual noise. I also have a fault code (4 led flashes) “single long duration limit opening”.
 

hvactechfw

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I have a similar problem with a Luxaire unit. I came home one evening and found the blower running even though the stat was off. I had to shut the power off to stop it any suggestions on this one? The blower motor is free and no unusual noise. I also have a fault code (4 led flashes) “single long duration limit opening”.

sounds like your main limit is stuck open. If the limit is open it means blocked air flow. Check your filter and make sure all your registers are open. You will need to replace the limit if it is stuck open and not resettable.
 

helios

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Do you know where the switch loction is? Its not a filter and i dont know how it would get blocked and all registers are open. could ths anomaly be the blower relay? Which just so happens to be mounted to a circuit board.
 

hvactechfw

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The limit is located to the left of the drat motor below the burner box. If the blower is not running then it could be the control board, motor, or capacitor.


 
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helios

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Sir we do not have a furnice this is a package unit w/heatpump. My suspicious are the same as yours blower motor board or capictor. I would like to isolate which one it is before i spend the money replacing any parts. Do you know how i can do this?
 

hvactechfw

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Reading back thru your posts I see you stated that blower motor runs. If this is the case it is not you motor or capacitor. I need more info on your unit to help you diagnose it. Model number? Sorry about the confusion it helps when you post your own thread instead of posting on anothers thread.
 

helios

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Ah, sorry about that. Okay model number AHP24B2AH21A serial number A0K6978957 and its a luxaire. I'll remeber your abvice in future postes.
 

mark30228

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Helios, did you ever find the reason for the code? I am having the exact problem with the fan motor continuously running and same error code (4-Single long duration limit opening) on a York heat pump air handler unit. When I look for a new control board online, it is the same as a Luxaire and I was hoping you could tell me whether it was the board or something else.
 

kok328

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Could be a bad thermostat. Check for power on the green wire while fan mode is auto or off.
 

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