Sure, but I need some more details about your HVAC system. Regardless, the HVAC objects have a field to specify a profile/schedule that's being used for availability. Here is an example of a DX coil from one of the reference building models.
Coil:Cooling:DX:SingleSpeed,
PSZ-AC:2_CoolC DXCoil, !- Name
ALWAYS_ON, !- Availability Schedule Name
AUTOSIZE, !- Gross Rated Total Cooling Capacity {W}
AUTOSIZE, !- Gross Rated Sensible Heat Ratio
3.66668442928701, !- Gross Rated Cooling COP {W/W}
AUTOSIZE, !- Rate
Here the third line references the ALWAYS_ON schedule, which in this model is defined as being 1 all the time. I suspect you will want something similar in your model, though where you put that depends on what type of HVAC system you have. Feel free to share your IDF file and I can try to be more specific, and confirm that this is your issue.
What are your settings for the HVAC availability profiles? If you are actually simulating for a full day but not seeing HVAC results, then it's likely that the system isn't running at night (which sounds reasonable).
Thanks bbrannon4. Can you please help me to find the option where I can check the HVAC availability?