System and method for diagnosing lack of coolant of vehicle to which integrated thermal management valve is applied

A system for diagnosing lack of coolant, the system comprising:

• an integrated thermal management valve including a plurality of valves which are openable and closable, and configured to selectively distribute coolant introduced from a head of an engine to front ends of a radiator, a heater, and an oil cooler;
• a controller configured to receive valve opening and temperature information from the above integrated flow control valve and coolant temperature sensor, and configured to determine whether the coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block and the coolant outlet as a valve on an outlet side connected to the radiator is open, and finally determine whether the coolant is insufficient by accumulating an increase amount of a temperature difference between the coolant outlet and the coolant inlet;
• wherein the controller determines that the coolant is insufficient when it is determined that the coolant temperature difference measured from the block and the coolant outlet is lower than or equal to a set temperature.
• wherein the controller continuously monitors an increase amount of the temperature difference between the coolant outlet and the coolant inlet when it is determined that the coolant is insufficient, and finally determines that the coolant is insufficient when it is determined that an accumulated factor value is greater than or equal to a set comparison value by accumulating different factor values for each continuous temperature difference.