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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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No power to my thermostat. it is a trane xr 401 or xr 402

Customer Question

no power to my thermostat. it is a trane xr 401 or xr 402 model. It is for a Trane AC/Heatpump unit.....5 tons.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


Please attach a well focused, close up photo of the wiring diagram glued inside the service panel,you can use the paper clip icon at the right end of the toolbar at the top of this dialog box,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If there is no paper clip icon, look for the '+attach files' link at left of your send button.

I can mark it up with trouble shooting instructions.

Customer: replied 1 year ago.
Not sure where the wiring diagram or which service panel you are referring to. Here are some pictures though. Hope this helps
Customer: replied 1 year ago.
Did you receive my photos?
Expert:  Phil replied 1 year ago.

Yes I just got your photo's thanks, ***** ***** photo's of the thermostat.... I need a photo of the wiring diagram that is a sheet of paper, about 8 x 11... sometimes a slight bit larger or smaller, glued to the inside of the blower service panel on the furnace or air handler.... that is where all the diagnosis is done and where the thermostat gets its power. ... and is where the wires that feed the thermostat come from.

We can go from there without a time limit.

Customer: replied 1 year ago.
I will try to locate it
Customer: replied 1 year ago.
Is this it?
Customer: replied 1 year ago.
I think it is probably this one
Expert:  Phil replied 1 year ago.

The second one is closer, it shows about 10% of the wiring, but I need the complete diagram it will look something like this.

Customer: replied 1 year ago.
I have to pick up my son soon. The pictures I sent to you are from the owners manuals that I have, and I do not see a diagram like the example you sent to me. I have not checked inside the panel to see if something is glued on there yet. I will do that a bit later after I return, and I will contact you again. Is it in the air handler unit or the outside unit?
Expert:  Phil replied 1 year ago.

Hello again, it will be inside the blower compartment access panel in the air handler, that is roughly 20" square, and generally lifts up an inch or so then pulls out, sometimes there are 2 screws that the bottom that need to be removed.