Trane factory does not support voltage changes due to UL required nameplate data tags that specify electrical information of the product.
Changing voltage voids UL listing because the nameplate data changes.
In the example in the title, assume you want to change 208v/ 1 phase to 277v/ 1 phase.
The motor is the same. See attached. 115 (with jumper added to the motor harness), 208/ 230 -277.
HOWEVER
We install a custom built TUTCO heater specifically designed for 208v/ 1 phase.
If you put 277v to that heater element it will likely burn up depending on the Kw.
Also, transformer is rated for 208, NOT 277v.
For these reasons the Trane factory does not approve any voltage changes.
You may try field modifications as a last resort
In summary, your local building inspector and your local UL representative has final authority over what could be allowed so it is best to work with them on any changes to electrical components for guidance.