Error code reference

Trane Furnace Error Code ERR 139

Communication failure

Communication failure – communication message detected while configured for 24V mode.

First step from the service manual

Check if mode of operation has been changed to 24VAC; change to COMM mode if needed.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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ERR 139 on my Trane Furnace

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Communication failure – communication message

From Service Manual 330506, p.38:

1.Check if mode of operation has been changed to 24VAC; change to COMM mode if needed.

2.Inspect the communication harness between the main control and the UI board for bent pins or unseated connectors at each end.

3.Measure supply voltage to the UI board. Expected: 5 VDC at the interface connector; a low or missing rail points back to the main control supply.

Part W10811169

User interface control board

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