Method for separate control of HVAC for a vehicle

A method for separate control of heating, ventilation, or air conditioning (HVAC) for a vehicle includes: determining if a set condition is satisfied, such that separate HVAC control is possible, when HVAC is performed; detecting a passenger count, an HVAC thermal load, and a relative humidity; performing HVAC in a first mode for front seats when no passenger is detected in the front passenger seat at the detecting step; selectively performing HVAC in a second mode for the front seats by comparing the HVAC thermal load with a set load; and adjusting a mixing ratio between inside and outside air, set depending on the relative humidity, by selectively reducing or increasing a quantity of inside air and a quantity of outside air depending on the passenger count.