JPH0160742B

PURPOSE:To reduce the number of connecting wires between indoor and outdoor units by a method wherein a contact of a first defrosting thermostat is connected in series with a timing relay motor of a second defrosting thermostat while a contact of the second defrosting thermostat is connected in series with a timing relay motor of the first defrosting thermostat. CONSTITUTION:In case where heat exchangers of first and second outdoor units are defrosted so that the surface temperature of each of the heat exchangers falls down below the set temperature of the first defrosting thermostat 14 and the set time for the timing relay motor 19 of the first thermostat 14 expires, the contact 16 of the thermostat is opened, an auxiliary relay coil 8 and a four- way valve coil 12 are deenergized and a defrosting operation for the first outdoor unit is started. In this case, since the contact 16 of the thermostat 14 is opened, the timing relay motor 18 of the second defrosting thermostat 15 of the second outdoor unit is deenergized. Thus, when a defrosting operation for the second outdoor unit is started, the first outdoor unit is so controlled that the defrosting operation for the unit is not started.