Loose wire in my furnace


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Old 10-20-20, 07:03 AM
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Loose wire in my furnace

I noticed a black wire coming out of a 24v relay that was loose. It was loose right beside the G and B/C connection but I'm not sure where it came out of.


The outside unit is a Trane XL-15i and the furnace is a Trane XV-95.
 
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Old 10-20-20, 09:05 AM
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You're showing a relay outside in the condenser..... not in the furnace.
Picture is small and hard to see. What is the red tape around the relay ??

It would most likely be attached to B/C..... not G.
I'd like to see a bigger picture of the relay with no gift wrapping.
 
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Old 10-20-20, 11:43 AM
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Last edited by PJmax; 10-20-20 at 05:17 PM. Reason: labeled pic/removed extras
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Old 10-20-20, 05:23 PM
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Thanks for the pics.

My apology. It looked like that relay was in the outside unit.
Ok.... to get right to it.

The two C terminals on the relay are the coil.
Terminals 1 and 3 are normally open.
The black definitely goes to the B/C terminal.
When 24v is applied to the coil via the white wire.... the relay closes sending switched 24v to the DEF terminal.

I'm trying to figure out what the board is with the DEF on it. Looks like a communication board.
Is there a part number on it you could post ?
Are there just two wires to the outside condenser ?


I'm trying to figure out the reason for that relay and why it's controlled by something outside.
 
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Old 10-21-20, 05:29 AM
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I'll try to get the part number, I think there are other wires coming out of the outside unit. Could DEF stand for "defrost"? Guess it might be some sort of a thing during cold weather...
 
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Old 10-21-20, 08:29 AM
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If that stands for defrost then you must have a heat pump. That would make your system dual fuel.
 
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Old 10-21-20, 09:03 AM
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Well the outside unit is a Trane XL15i single-stage heat pump: https://www.furnacecompare.com/mfr/t...t-pumps/xl15i/

I am running on natural gas and electricity.
 
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Old 10-21-20, 01:46 PM
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So there are a few wires connected from the outside unit to that board (only says power on it couldn't find any other names on it) :
  • orange cable that goes to O/B
  • black cable that goes to C
  • red cable that goes to R

I connected that loose black cable to B/C hope that was it...
 
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Old 10-21-20, 02:10 PM
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It may be some type of dual fuel board. I've been trying to find it in Trane's tech area.
 
 

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