Correct. However, I'm not sure what kind of functionality you will get with OVMS, so it would be helpful to post back here when you get it working.
Apparently mine does have a TCU, because when I try to turn on AC, the logs say:
...
I (2645914) v-nissanleaf: CommandClimateControl
I (2645914) v-nissanleaf: RemoteCommandHandler
I (2645914) v-nissanleaf: Sending Wakeup Frame
I (2645914) ovms-server-v2: Send MP-0 c26,0
I (2646014) v-nissanleaf: RemoteCommandTimer 24
I (2646014) v-nissanleaf: OLD TCU on EV Bus
I (2646014) v-nissanleaf: Sending Wakeup Frame
I (2646014) v-nissanleaf: Enable Climate Control
I (2646114) v-nissanleaf: RemoteCommandTimer 23
I (2646114) v-nissanleaf: OLD TCU on EV Bus
I (2646114) v-nissanleaf: Sending Wakeup Frame
I (2646114) v-nissanleaf: Enable Climate Control
I (2646214) v-nissanleaf: RemoteCommandTimer 22
I (2646214) v-nissanleaf: OLD TCU on EV Bus
I (2646214) v-nissanleaf: Sending Wakeup Frame
I (2646214) v-nissanleaf: Enable Climate Control
I (2646314) v-nissanleaf: RemoteCommandTimer 21
...
repeating with RemoteCommandTimer decreasing.
Is that inference correct?