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Defrosting – why am I getting alarms?

Getting a high-temperature alarm when everything looks fine? During defrosting, the temperature rises for a short time to melt ice. If IWMAC triggers an alarm too quickly, that normal spike can look like a problem. Here's how to spot a false alarm, set the right delay, and know when it's time to take action.

  • Maria Sotberg

    Writer

published

updated

Refigeration isle and defrosting.
Photo by Bernard Bodo / Adobe Stock.

Getting a high-temperature alarm when everything seems fine? In many cases, your unit is simply defrosting.

During defrost, the temperature rises briefly to melt ice. That is normal. But if your alarm settings don't allow for that short spike, you may get an alarm even though nothing is wrong.

Why defrost

Watch for ice that returns quickly
If ice comes back soon after defrosting, something is not right. It could be a door issue, poor airflow, incorrect settings, or a fault in the defrost system. If you are unsure, ask your service partner to check it. 

Refrigeration and freezer units need regular defrost cycles to remove ice. Ice builds up when warm, moist air enters the unit. This can happen when doors open, goods are moved in and out, or door seals are not closing properly. This ice can block airflow, make the unit work harder, and waste energy.

During defrosting, the temperature rises briefly. If temperature thresholds in IWMAC are set without accounting for defrost, the temporary temperature rise will exceed the threshold and trigger an alarm. This is a "false" alarm – there is no actual fault.

Find the right defrosting routine:

Defrosting made easy - take control of the ice

The quick fix: set an alarm delay

The easiest way to avoid false alarms is to add an alarm delay. This tells IWMAC to wait before sending the alarm. If the temperature drops back to normal after defrosting, no alarm is sent. If it stays too high, you still get warned.

  1. Log in to "Service mode" on your facility.
  2. Go to "Alarm settings".
  3. Find the temperature alarm for the unit in question.
  4. Set a delay of 15 – 30 minutes.
  5. Save.
IWMACs interface with refrigeration and cooling counters, temperatures, alarms and statuses like defrosting.
Image: Easy interface with refrigeration and cooling counters, temperatures, alarms and statuses like defrosting.
Unit typeTypical defrost timeRecommended delay
Refrigerated cabinet/cold room10 – 20 minutes20 – 30 minutes
Freezer cabinet/freezer room15 – 30 minutes30 – 45 minutes
Support page:

Understanding defrost alarms in IWMAC

When to take action

If the alarm clears soon after defrosting, you usually do not need to worry. If it stays active for more than 45 – 60 minutes, it is worth checking the unit.

  • Is the door closed properly?
  • Are the seals damaged or dirty?
  • Is the airflow blocked?
  • Is there heavy ice build-up?
  • Is the fan or compressor running?

If the alarm keeps coming back, or the unit does not return to normal temperature, contact a service partner.

Smart defrosting tips

  • Do not defrost more often than needed: too much defrosting wastes energy.
  • Watch for ice build-up: repeated ice build-up often points to a setting or airflow issue.
  • Keep airflow clear: do not block vents with products.
  • Check doors and seals: warm air getting in creates more ice.
  • Use IWMAC data: look for patterns instead of guessing
Read the article:

Why you need a refrigeration maintenance schedule – and a daily task checklist

Learn more about refrigeration and cooling – view our latest articles and tips

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