Outdoor unit of air conditioner and method for controlling the same

An outdoor device for an air conditioning system, comprising:

• a tank to store defrosting liquid;
• a nozzle to apply defrosting liquid from the tank to a heat exchanger;
• a valve to control flow of the defrosting liquid between the tank and nozzle;
• a defrosting liquid tray to collect the defrosting liquid passing through the heat exchanger;
• a concentration sensor provided in the defrosting liquid tray to detect a concentration of the collected defrosting liquid;
• a defrosting liquid level sensor in the defrosting liquid tray to detect a liquid level of the collected defrosting liquid;
• a supplement defrosting liquid tank to selectively supply supplement defrosting liquid to the tank;
• a supplemental liquid valve having an adjustable opening degree to supply the supplement liquid into the tank from the supplement liquid tank;
• and
• a controller to control the valve based on a temperature of the heat exchanger and a number of times the valve has been set to an open state during a heating mode of the air conditioning system, wherein the controller determines an amount required to fill the tank with the supplement defrosting liquid from the supplement defrosting liquid tank, on the basis of a concentration of a collected defrosting liquid detected by the concentration sensor, wherein the controller adjusts an opening degree of the supplement liquid valve when the concentration of the defrosting liquid detected by the concentration sensor is less than a predetermined concentration, and wherein the controller operates the pump to pump the defrosting liquid into the tank from the defrosting liquid tray, which is provided at a position lower than a position of the tank, when a liquid level of the defrosting liquid detected by the defrosting liquid level sensor is greater than a predetermined liquid level.