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REFRIGERATION

Troubleshooting

Evaporator coil iced up

The evaporator is the cold coil inside the cabinet, usually behind a cover with a fan. A light, even frost on it is normal and is cleared by the defrost cycle. Trouble starts when frost turns into a solid block of ice. Air can no longer pass through the fins, the fan may jam, and the cabinet warms even though the compressor runs non-stop. Ice forms when moisture enters faster than defrost can remove it, or when defrost stops working. Monsoon humidity and doors opened all through service make Indian kitchens especially prone to it. A manual defrost restores cooling, but unless you find the cause, the ice will be back within days.

First, check these

  1. Look through the fan grille or remove the cover only if it is a tool-free clip-on panel. Note whether the ice is even across the coil or concentrated in one area.
  2. Check that air is blowing from the fan outlet and the fan is not grinding against ice.
  3. Check the door gasket and whether the door is being left ajar or propped open during prep.
  4. Look at the drain under the evaporator. If water cannot drain away, it refreezes into the coil.
  5. Check the controller for a defrost symbol or a defrost-related alarm, and whether the defrost schedule has been changed.

Likely causes

  1. 1. Warm, humid air entering through door or gasket

    You can check this

    Signs: Heavy, feathery frost, worst near the door side of the coil; problem worse in monsoon and during busy service.

    Fix: Fix or replace damaged gaskets, keep doors closed between uses, fit a door closer or strip curtain where suitable, and avoid storing uncovered hot or steaming food.

  2. 2. Blocked evaporator drain

    You can check this

    Signs: Clear, glassy ice at the bottom of the coil and in the drain tray; water dripping inside the cabinet.

    Fix: After a full defrost, flush the drain with warm water. On freezers, if the drain refreezes every cycle, the drain line heater may have failed and needs a technician.

  3. 3. Defrost heater or termination sensor failure

    Technician job

    Signs: Ice builds steadily across the whole coil even with good door discipline; no water appears in the drain after a scheduled defrost.

    Fix: A technician tests the heater, the defrost termination sensor or thermostat and replaces the faulty part.

  4. 4. Controller defrost settings wrong

    Technician job

    Signs: Defrost interval too long or duration too short for the conditions, settings changed after a service or reset.

    Fix: A technician should set the defrost interval, duration and termination temperature to suit the unit and your humidity. Do not change these parameters without the manual.

  5. 5. Evaporator fan failed

    Technician job

    Signs: No airflow from the outlet, frost heavy in front of the fan, cabinet warm.

    Fix: Defrost, then check if the fan turns freely. A seized or burnt motor must be replaced by a technician.

  6. 6. Low refrigerant charge

    Technician job

    Signs: Ice or frost only on the first part of the coil near where refrigerant enters, the rest clear; cooling slowly worsening.

    Fix: Needs a technician for leak detection, repair and a weighed recharge.

When to call a technician

Do one manual defrost: move stock to another cold unit, switch off and isolate power, leave the door open with towels and a tray to catch water, and let the ice melt naturally. If ice returns within a few days with sensible door use, the defrost system, fan or charge needs a technician. Tell them how fast it came back and where it formed.

Never hack at ice with knives or screwdrivers, and do not use a gas torch or heat gun. A pierced coil releases refrigerant, which in hydrocarbon units (R290 or R600a) is flammable. Keep power isolated while ice melts and water is present.

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