Kenneth P Centerville , GA September 22, 2014 Appliance: Samsung Refrigerator RS2578BB/XAA Samsung Refrigerator Rs2578bb/Xaa: Bad defrost heater and sensor (display showing code 3 at startup). How to replace Refrigerator Door Switch. Purchased new evaporator/heater/sensor assembly from appliance parts. Removed new heater, sensor and wire harness from new assembly and from existing unit in refrig section. Then installed new heater and sensor on old refrig evaporator, avoiding complex soldering and recharge with Freon. Once repaired all failure indications cleared and refrigerator section performing like new. Also purchased new heater for water tank and several broken plastic parts that went in in 2 minutes. Changed door light switch which had become intermittent. 25 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours