HVAC system of vehicle

A heating, ventilating, and air conditioning (HVAC) system of a vehicle, the HVAC system comprising:

• a battery cooling line provided to circulate a first coolant through a first radiator, a battery core, and a first valve;
• an electronic component cooling line provided to circulate a second coolant through a second radiator, an electronic component core, and a second valve;
• a branch line provided to have a first end portion branched from the first valve and a second end portion connected to an upstream point of the battery core, wherein a main heat exchanger is disposed between the first end portion and the second end portion of the branch line;
• an auxiliary line provided to have a first end portion branched from the second valve and a second end portion connected to an upstream point of the electronic component core, and to pass through the main heat exchanger to perform a heat transfer with the branch line;
• and
• a controller configured for circulating the first coolant and the second coolant in the branch line and the auxiliary line, respectively, and performing the heat transfer in the main heat exchanger by controlling the first valve and the second valve when a temperature of the battery core is required to be increased.