Do you have the hvac module?
There side there may be something about the setup of your problem that doesn't allow it to be turned on. Maybe elaborate about the setup or have you tried a really simple room with air?
Could be a bug. Did this ever work? What versions and service pack?
Thank you Jared for your reply.
I'm not professional using Flow Simulation, what did you mean by HVAC module.
HVAC is additional flow module for calculation ie. air condition. And this additional module allowe to calculate comfort parameters.
You can buy it from VAR and this module will be attached to your flow license.
There are two additional modules
HVAC - cooling and air conditions
Electronics cooling - for cooling electronics