Defrost heaters do not run that much. In the OLD refer mechanical control's, the defrost heaters were on a mechanical timer. In the newer electronic control refers, I would bet it is on a temp sensor control instead of a timer, but you need to find out. The purpose of the defrost heaters is to remove the ice buildup from the evaporator/s. The ice restricts the air flow thru the evap fins and causes a loss of cooling in the refer. So, if you turn the Heaters OFF, you may cause a faster ice build up and that would cause the refer to run LONGER to maintain your temp. So, it would be a trade off on power consumption----either the defrost heater would run or the compressor would run longer due to the defrost heater not removing the ice build up. Doug
