METHOD FOR CONTROLLING DEFROST OPERATION FOR COOLING/HEATING AIR CONDITIONER

摘要

PURPOSE: A method for controlling defrost operation for cooling/heating air conditioner is provided to reduce frequency of defrost operation by setting the accumulated defrost cycle duration time to be different according to the outdoor temperature range. CONSTITUTION: A method comprises a step(S410) of judging whether the coil temperature for an outdoor heat exchanger is lower than 0 Deg.C; a step(S411) of comparing the measured outdoor temperature with a third temperature(c), if the coil temperature is lower than 0 Deg.C; a step(S412) of judging whether a first set time(N1) has lapsed; a step(S413) of setting the accumulated defrost cycle as a second set time(N2) if the coil temperature is lower than the freezing point and the measured outdoor temperature is higher than the third set temperature and lower than the second set temperature; a step(S414) of judging whether the second set time has lapsed; a step(S415) of setting the accumulated defrost cycle as a third set time(N3) if the coil temperature is lower than the freezing point and the measured outdoor temperature is higher than the second set temperature and lower than the first set temperature; a step(S416) of judging whether the third set time has lapsed; a step(S417) of judging whether the fourth set time has lapsed; a step(S422-S426) of performing defrost operation by turning off the indoor and outdoor fans, compressor and four-way valve, and turning on the compressor; a step(S428,S430) of judging whether the coil temperature is higher than a predetermined level, and turning off the compressor is the coil temperature is higher; a step(S432,S434) of turning on the four-way valve and turning on the compressor and outdoor fan; a step(S436,S438) of judging whether the coil temperature is higher than the temperature(Z) for heating, and heating the indoor area by turning on the indoor fan if the coil temperature is higher.