Why your commercial refrigeration keeps icing up

Ice build-up in a commercial fridge or cold room is more than just an annoyance. It reduces valuable storage space, making it harder to organise stock efficiently. Ice can also disrupt airflow, causing temperature fluctuations that put your products at risk of spoilage. Over time, this added strain forces refrigeration components to work harder, increasing energy costs and raising the chance of expensive breakdowns. If left untreated, ice build-up can damage door seals, block drainage systems, and even lead to safety hazards for staff.

Addressing the problem quickly and correctly helps maintain consistent temperatures, protects your stock, and keeps your refrigeration running smoothly.

First checks when your commercial fridge ices up

Before you assume the worst, start with a few simple observations. Many icing problems come down to warm, moist air getting into the system or poor airflow over the evaporator coil.

Stand in front of the unit and look for obvious clues. Is there heavy frost on the evaporator, thick ice around the door frame or a block of ice on the floor near the drain? These details help you follow a logical troubleshooting path.

• Note where the ice is forming – door, ceiling, floor, coil, around fans or drains

• Listen for fans – are they running smoothly, intermittently or not at all?

• Check product condition – part-frozen or soft stock can indicate temperature swings

• Look at the door – is it fully closing, or sitting slightly open?

These quick checks are safe for your team and give a good starting point for any engineer you call in.

Decision guide: matching ice build-up to likely causes

Ice around doors and thresholds

If you see ice forming on door frames, thresholds or curtains, the problem is usually warm air ingress. This often comes from damaged door seals or poor door discipline during busy periods.

Inspect the gaskets all the way round. Look for splits, flattened sections or areas where paper can be pulled out when the door is shut. Also watch how staff are using the door during service.

Heavy frost on the evaporator coil or fans

When the evaporator is covered in thick frost or solid ice, it is a sign that moisture is freezing faster than the defrost cycle can clear it, or the defrost is not functioning correctly. This restricts airflow and drives temperatures up.

Typical causes include failed defrost heaters, an incorrect or faulty defrost timer, fans not running, or low refrigerant levels affecting coil temperature. These faults need an engineer, but your team can safely check for obvious obstructions or ice preventing the fan blades from turning.

Ice on floors and around drains

Ice patches on the floor near the evaporator or under shelving often point to blocked drains. As the unit goes into defrost, melt water cannot escape and refreezes along the coldest surfaces.

Look for standing water in drain trays, or ice forming directly over drain covers or grilles. Light, careful cleaning around the drain entry with non-metallic tools or cloths is safe, but deeper clearing of pipework should be left to an engineer.

Ice build-up behind product or shelving

If you find ice behind cases of stock or at the back of display fridges, the likely cause is airflow restriction. When product is pushed hard up against the evaporator or back panels, air cannot circulate properly.

In these cases, simply rearranging stock so there is a gap in front of vents and coils can make a rapid difference. Overloading shelves and stacking items high in front of air paths is a common operational issue.

Safe checks your site team can carry out

Your facilities or store team can do several safe, non-technical checks that often help reduce icing and prepare for an engineer visit.

Start with a full visual inspection. Clear any boxes, packaging or trays that are obstructing vents, fan guards or evaporator housings. Ensure air can move freely from the coil across the cabinet or room.

Next, focus on door closure. Clean debris from door thresholds, check that self-closing devices are working and adjust any floor mats or pallets that might be catching the door. Repairing or replacing damaged gaskets should be booked with an engineer, but spotting the issue is a useful first step.

• Keep product at least a few centimetres away from vents and coils

• Limit the time doors are held open during deliveries

• Check that night blinds on display cases are intact and used correctly

Always record what you find, including any temperature alarms or error codes, so your refrigeration specialist has a clear picture of the fault history.

What your team should avoid doing

Being proactive is helpful, but some well-meant actions cause more harm than good. Chipping away at ice with screwdrivers, knives or other sharp tools can easily puncture coils, damage seals or injure staff.

Similarly, pouring boiling water onto ice, especially near electrics, is a serious safety risk. Sudden temperature shocks can crack plastic housings or glass, and uncontrolled run-off can enter electrical components.

Avoid adjusting defrost timers or control settings unless you are qualified and have the correct documentation. Incorrect settings can mask the real fault and lead to further icing or food safety issues.

What an engineer will test on an icing system

When you call a refrigeration engineer, they will start by confirming the basics your team has already observed. They will then test the defrost cycle to ensure it is operating at the right intervals and durations for the application.

Using electrical test equipment, they will check the continuity and performance of defrost heaters, door heaters (if fitted) and fan motors. They will also confirm that fans are running during the correct parts of the cycle and that air paths are clear.

The engineer will inspect and clear drain lines, trace any frozen sections and check for correct fall so that condensate drains away properly. Where low refrigerant is suspected, they will take pressure readings, look for leak indicators, and follow industry procedures for leak detection and repair.