When using a Symbio condenser with a UC/Symbio 400B equipped Blower/Fan Coil unit, the 400B in the indoor unit is the system controller. Fan, electric heat and any other system control will rely on the 400B. The 400B provides 24vac on J17-4 and the outputs for the compressors and reversing valve are switched grounds.
See below for an example wiring diagram to a Residential 5TWA40xx Heat Pump