Trane ACONT900AC43UA Service Manual page 17

4 Heat/3 Cool/ Heat Pump
Communicating Programmable 3-Wire Hookup
Step 6
Press the Done key to exit the Installer Setup.
Note:
Manually changing an ISU setting to an option other than "E"
disables Discovery mode for that ISU setting. If power is lost,
all custom settings are retained in the memory.
(A/T)CONT900AC43UA Installer Guide
Table 4. Installer Setup Menu.
C - A 9