If the reversing valve is getting power during heat cycle, other than
during the defrost cycle, it is getting that power from one of three
paces: the thermostat, a short in the wiring between the tstat and air
handler or the air handler and condensing unit, or a faulty defrost
board. Anything is possible of course, but I do not recall ever seeing
this particular problem with a thermostat or defrost control. Disconnect
the orange wire from the thermostat and if the problem continues, it is
not the thermostat. Then disconnect the O wire at the condensing unit.
If the problem continues, it would indicate the defrost board. If not,
the wiring. Good luck Larry