R-Pro › Field cases › Refrigeration systems

Defrost Heater Open Circuit / Failure

Likely causes

Heater element open circuit (end of life)

Check: Measure heater resistance (open circuit = infinite)

What to do: Measure heater resistance (open circuit = infinite) → Check thermal fuse continuity → Inspect entire heater circuit (wiring, terminals, fuse) → Replace with heater of same spec (voltage, wattage, shape) → Run defrost cycle after replacement to confirm operation → Also check defrost drain flow

Heater terminal corrosion or poor contact

Check: Check thermal fuse continuity

What to do: Check thermal fuse continuity → Inspect entire heater circuit (wiring, terminals, fuse) → Replace with heater of same spec (voltage, wattage, shape) → Run defrost cycle after replacement to confirm operation → Also check defrost drain flow

Defrost circuit cut by thermal fuse activation

Check: Inspect entire heater circuit (wiring, terminals, fuse)

What to do: Inspect entire heater circuit (wiring, terminals, fuse) → Replace with heater of same spec (voltage, wattage, shape) → Run defrost cycle after replacement to confirm operation → Also check defrost drain flow

Field tip

Defrost heater has an open circuit and is not defrosting. Replace with same specification heater.

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