CIRCUIT TO PROTECT AIR CONDITIONER FROM MISTAKEN CONNECTION

PURPOSE:To make it possible to prevent the breakage of an element even if it is connected by mistake by supplying electric power through a fuse and resistor separately from a control circuit on the side of the indoor unit to a serial circuit consisting of a relay contact point for operation on the side of the indoor unit and electric current detection circuit and a serial circuit consisting of a relay contact point for driving a four-way valve and electric current detection circuit. CONSTITUTION:A serial circuit which includes a relay contact point 7 to operate an air conditioner on the side of the indoor unit 3 and a current detection circuit 17 and a serial circuit which includes the contact point 16 of a relay to drive a four-way valve for switching room cooling and room heating and an electric current detection circuit 17 are connected to the R phase through a fuse 14 and resistor 15. On the other hand, a control circuit 5 on the side of the indoor unit is supplied electric power from the R phase through another fuse 14'. Accordingly if the connection of either a connection line 12 or 13 of the indoor unit 3 and outdoor machine 4 is mistaken, the electric current is restricted by a resistor 15 before either the relay contact point 7 or 16 is welded or the element breakage in the electric current detection circuit 8 or 17 occurs, and, furthermore, the fuse 14 blows. It is, therefore, possible to avoid serious trouble due to a mistaken connection and it can be repaired only by replacing the fuse.