furnace pressure sensor switch


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Old 11-21-13, 02:03 PM
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furnace pressure sensor switch

Warning light blinks three times and guide on the panel indicates that it is the pressure sensor switch. What can I do before calling a repairman to replace the switch?
 
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Old 11-21-13, 02:08 PM
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Welcome to the forums.

A make and model of the furnace would be a help for starters.

Is the draft inducer blower running ? (little fan up top that starts before the burner)
The pressure switches very rarely go bad.
 
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Old 11-25-13, 05:32 PM
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The furnace is by Trane and the model is XR90.
The draft inducer blower is running. I pulled the hose connected to the inducer blower and blew the little water in the tube.
Even when the warning light is blinking, the furnace is working. There is heat (hot air) is coming out of the register when the furnace kicked on.
Anything else I could do myself without calling for repair.
 
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Old 11-25-13, 08:12 PM
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XR-90 is a trade name not a model number. You need to remove the front access cover and it should be posted on the side.

That tube needs to be clear as well as the little hole in the draft inducer where the hose connects.
 
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Old 11-26-13, 08:41 AM
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The model # is 2TXCC043BC3HCAA, The serial # is 72916FX5G, MFG Date is 7/2007.
I removed the tube from draft inducer on both ends and cleared the tube and the hole on the draft inducer. I removed all the tubes that empty into the small sump pump and cleared the tubes. There was a small amount of water in the small tray of the sump pump and I vacuumed it dry and reconnected all the tubes.
When the furnace is running the warning light blinks continuously. The chart on the panel indicates that it is normal. When no heat is called for the warning light still blinks in sequence of three.
 
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Old 11-26-13, 09:52 AM
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Check your lower drain lines and make sure all are clear. If you have water in the tube going to the pressure switch, you have blockage lower. Not sure of your model but some Tranes needed the trap to be primed with water before they would work properly.
 
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Old 11-26-13, 05:28 PM
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Red face

Ynot, you may have a bad pressure switch, do you have a volt meter? If so you can test across the pressure switch to see if it's closed or not?

Also, obstructions in the pvc flue can prevent the pressure switch from closing too! The pressure switch won't close if there's any issues with the venting system. So not only a bad draft inducer can prevent the pressure switch from closing, but water backed up in the furnace, a blockage in the venting system, a plugged vacuum port, these types of things can keep the switch from making.
 
 

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