Defrost Timer System (Mechanical Timer)
Every 8 hours of compressor run time defrost timer activates radiant electric defrost heater suspended from evaporator. After about 20-30 minutes (depending on the timer used) of defrost cycle time, timer restores circuit to compressor.
Defrost terminator (thermostat) is wired in series with defrost heater. Terminator opens and breaks circuit when preset high temperature is reached. After defrost thermostat opens, thermostat remains open until end of defrost cycle when cooling cycle starts and terminator senses present low temperature and closes.
Defrost heater is suspended from the evaporator coil across the bottom to keep defrost drain free flowing during defrost. Defrost water is caught in trough under evaporator coil and flows through drain hole in liner and drain tubing into drain pan. Air circulated by condenser fan over pan evaporates water.
Adaptive Defrost System (Electronic Control Board)
The ADC adapts the compressor run time between defrosts to achieve optimum defrost intervals by monitoring the cold control and length the defrost heater is on.