Refrigeration system defrost control

Claim 1

IN A CONTROL ARRANGEMENT FOR A REVERSE CYCLE REFRIGERATION SYSTEM SELECTIVELY ENERGIZABLE TO HEAT AND COOL INCLUDING COMPRESSION MEANS, AN OUTDOOR COIL AND AN INDOOR COIL CONNECTED IN REFRIGERANT FLOW RELATIONSHIP TO COOL, AND MEANS FOR REVERSING THE FLOW OF REFRIGERANT THROUGH SAID INDOOR COIL AND SAID OUTDOOR COIL TO HEAT, THE COMBINATION COMPRISING CONTROL MEANS FOR REGULAING OPERATION OF SAID REVERSING MEANS TO DEFROST SAID OUTDOOR COIL; FIRST CONDITION RESPONSIVE MEANS ADAPTED AT A PREDETERMINED FIRST OUTDOOR COIL CONDITION TO READY SAID CONTROL MEANS FOR ENERGIZATION; FIRST TIMING MEANS ADAPTED PERIODICALLY TO READY SAID CONTROL MEANS FOR ENERGIZATION, SAID CONTROL MEANS BEING ENERGIZED UPON SIMULTANEOUS ACTUATION AND SAID FIRST CONDITION RESPONSIVE MEANS AND SAID FIRST TIMING MEANS TO DEFROST SAID OUTDOOR COIL; AND MEANS FOR REGULATING THE DURATION OF SAID OUTDOOR COIL DEFROSTING TO INSURE RESTORATION OF SAID OUTDOOR COIL TO AT LEAST A PREDETERMINED SECOND CONDITION INCLUDING SECOND CONDITION RESPONSIVE MEANS ADAPTED AT SAID PREDETERMINED SECOND OUTDOOR COIL CONDITION TO READY SAID CONTROL MEANS FOR DEENERGIZATION, AND SECOND TIMING MEANS ADAPTED UPON THE EXPIRATION OF A PREDETERMINED TIMED INTERVAL TO READY SAID CONTROL FOR DEENERGIZATION, SAID CONTROL MEANS BEING DEENERGIZED UPON SIMULTANEOUS ACTUATION OF SAID SECOND CONDITION RESPONSIVE MEANS AND SAID SECOND TIMING MEANS, SAID FIRST CONDITION RESPONSIVE MEANS BEING EFFECTIVE AT THE OCCURRENCE OF A PREDETERMINED THIRD OUTDOOR COIL CONDITION DURING SAID TIMED INTERVAL TO INTERVENE AND DEENERGIZE SAID CONTROL MEANS TO TERMINATE OUTDOOR COIL DEFROSTING.