Pw M Palos Heights , IL April 01, 2021 Appliance: Electrolux Refrigerator EW28BS85KS4 Electrolux Refrigerator Ew28bs85ks4 / : Ice build up in fresh food compartment rust on back of refrigerator in upper right hand corner. How to replace Defrost Heater. I removed the fresh food ice maker found the drain tube for ice maker frozen. This was causing the back of the unit to rust out. This also caused the water to run down the back of the unit the into the duct work and into the freezer causing ice buildup. I then defrosted the freezer removed the rear duct work and the freezer drain pan cover. I found the freezer drain was not draining. I removed the exterior rear cardboard cover and located the freezer drain tube removed it and found that it was blocked by material that must have been there since the unit was manufactured and did not let the water to drain. Cleared blockage reinstalled drain. I installed the retro fit kit that I purchased that replaces original air handler part #AP6039735. This kit has a better seal and an improved defroster heater shield. So far so good. 17 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 2+ hours