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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a trane XR90 that is blowing cold to somewhat warm

Customer Question

Customer: ***** *****. I have a trane XR90 that is blowing cold to somewhat warm air.
JA: Thanks. Can you give me any more details about your issue?
Customer: I installed a nest thermostat a week ago. Everything seemed fine, but then yesterday I guess it ran all day dumping out cold air.
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Submitted: 11 months ago.
Category: HVAC
Customer: replied 11 months ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Phil replied 11 months ago.

Hello,

please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to be taken from straight on, in very good light.

You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here.,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If you have an error code showing, tell me what the code read out is on the wiring diagram or a sticker next to the diagram please.

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.

We can go from there.

Customer: replied 11 months ago.
The picture was mostly gone on the service panel so I found a copy in the manual. I wasn't sure what you meant by the thermostat wires so I took a picture of the connections.
Customer: replied 11 months ago.
It finally started dumping out hot air. Not sure why but I'm not complaining.
Expert:  Phil replied 11 months ago.

THanks, ***** ***** it fails, after the house is warmer hopefully, do this test on the printed circuit board in the furnace.

Use a hair drier to slowly warm the printed circuit card up to120F or a bit warmer, but not over 140F... if there is any change in the error codes or other furnace behavior... the card has a cracked micro circuit that opens and closes as the card expands and contracts... that proves a bad printed circuit card.

No change however does not prove the card is good however... but a change proves the card is definitely bad.

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After that test is complete

http://screencast.com/t/YofMvzwaDQf

Let me know what you can discover, we can go from there.

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