I use a simple EMS program for turning off DX coils below a specified outdoor temperature. Something similar may work for you and humidity ratio.
EnergyManagementSystem:Sensor
OutdoorTemp
Environment
Site Outdoor Air Drybulb Temperature
EnergyManagementSystem:Actuator
DXLowLimit1
Sched_LowTempClgOFF
Schedule:Compact
Schedule Value
EnergyManagementSystem:ProgramCallingManager
DXLowLimit Management1
BeginTimestepBeforePredictor
DXCoilControl1
EnergyManagementSystem:Program
DXCoilControl1
IF (OutdoorTemp < 12.8)
SET DXLowLimit1 = 0.0
ELSE
SET DXLowLimit1 = Null
ENDIF