Where to connect C wire - Trane XE900

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  #1  
Old 11-23-17, 06:26 PM
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Where to connect C wire - Trane XE900

Hi,

I'm looking to change my current thermostat and I'll need a C wire. I have unused wires coming from the furnace to the thermostat, however I have no clue where to connect the C wire. The compressor is a Trane XE900 and runs heat pump and A/C.

I have 4 wires in use in my current thermostat.
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This is the schema
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And a picture with, where I think I have to connect the C wire
Name:  Furnace.jpg
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Could you help me?

Thanks
 
  #2  
Old 11-23-17, 06:43 PM
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Bottom picture - go a bit lower and zoom in on the left and post again. The blue wire is most likely the C you need. It should also be connected to a wire going to your outside compressor as the compressor needs a C as well.
 
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Old 11-23-17, 09:18 PM
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Here is the picture
Name:  Cables.jpg
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Old 11-23-17, 09:32 PM
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Yup. That thick blue wire in the front is C. For sanity use the spare unused blue wire to go to the thermostat. Remove the blue wire nut - add the thin blue wire - then put the wirenut back on - will have thick blue, thin blue, and the old white.

Are you sure that you have a heat pump? The thermostat wiring is only set up for a/c and electric coil heat.
 
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Old 11-23-17, 09:32 PM
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It's hard to read the colors in that schematic. The C connection is also grounded in that air handler so any metal chassis connection will yield C.

Agreed.... blue wire. Was able to read Bl off the print.
 
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Old 11-23-17, 09:41 PM
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Thank you very much.

Not sure about the heat pump, I thought I read it somewhere when I was trying to find an answer to my question in Google.
 
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Old 11-23-17, 09:55 PM
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The XE-900 shows it can be a heat pump. But you'd need to post the actual model number off the condensor unit for confirmation.

If it was a heat pump...... the outside condensor would be running in the winter.
Does that happen ?
 
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Old 11-24-17, 12:57 PM
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No, I don't recall it happening, I've only heard the compressor when on A/C.
 
 

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