Commercial refrigeration · Kent
Freezer icing up or frosting over
A commercial freezer that keeps frosting over is rarely a one-off nuisance. It usually points to a door seal, defrost cycle or airflow fault that will get worse, and more expensive, the longer it runs. Here is how to work out what is happening before you pick up the phone.
Quick answer
Ice building up inside a commercial freezer almost always comes down to warm, moist air getting in and freezing on the coldest surfaces. The most common causes, in order of likelihood:
- A worn or torn door seal. A failed gasket lets warm kitchen air in continuously.
- The door left open or propped during busy service or deliveries.
- A failed or mistimed defrost cycle, so ice never clears properly.
- Blocked evaporator airflow from an existing ice build-up feeding itself.
- A refrigerant or thermostat fault causing the evaporator to run too cold for too long.
Light frost on the back wall overnight is normal. Thick ice on the door frame, floor or shelving is not, and it means the unit is losing efficiency by the hour.
What to do before calling an engineer
A few checks now can save an engineer's visit, or at least speed up the fix when they arrive.
- Inspect the door seal: run a hand along the gasket for splits, flattening or gaps. Shine a torch around the closed door from outside; light showing through means a failed seal.
- Check the door closes fully: a bent hinge, damaged handle or stock pressed against the door can stop it sealing, even with a good gasket.
- Note where the ice is forming: back wall only usually means airflow or defrost. Door frame and floor ice points to a seal or door discipline problem.
- Check staff habits: doors left open during prep or deliveries is one of the most common causes we find on site visits.
- Listen for the defrost cycle: most units run an automatic defrost every 6 to 8 hours. If you never hear it, or ice never reduces after it, the defrost heater or timer may have failed.
- Record the temperature: a rising cabinet temperature alongside ice build-up suggests a refrigerant fault, not just a seal issue.
- Do not chip or scrape ice off the coils: this can puncture the evaporator and turn a seal repair into a full refrigerant system replacement.
⚠️Call an engineer immediately if
Some symptoms mean the unit is failing, not just frosting, and food safety is at risk.
- Cabinet temperature is above minus 18°C and climbing, with frozen stock at risk.
- Ice has built up thick enough to stop the door closing or opening fully.
- The compressor runs constantly with no cycling off.
- Water is pooling on the floor around the unit, a slip hazard and a possible drain or defrost fault.
- You smell anything unusual, such as a chemical or burning odour, near the compressor or evaporator.
Get it looked at before stock is at risk
Our engineers cover freezer, fridge and cold room faults across Folkestone and the wider Kent coast, with fast diagnostics and parts for Foster, Williams, Hoshizaki and Scotsman equipment.
📞 Call 01304 873469 Book an engineerNext steps
Fridge not getting cold?
The four common causes when a commercial fridge runs warm, cycles constantly or makes noise.
Read the guide →Cold room not holding temperature?
Door seals are often the cheapest fix for chronic icing and temperature drift.
Read the guide →Refrigeration maintenance plans
Scheduled servicing catches seal wear and defrost faults before they cause ice damage.
See service agreements →Frequently asked questions
Why does my freezer keep icing up even with a new door seal?
If icing continues after a seal replacement, check the door hinges and closer mechanism. A door that does not sit flush will still let air in even with a perfect gasket. A failed defrost timer or heater is the next most likely cause.
Is a little frost on the back wall of a freezer normal?
Yes. A thin, even layer of frost that reduces after each automatic defrost cycle is normal. Thick ice that builds up between cycles, or ice on the door and floor, is not.
Can I defrost a commercial freezer myself?
You can switch off and allow a manual defrost for light ice, provided stock is moved to another unit first. For persistent icing, a manual defrost only buys time. The underlying seal, hinge or defrost fault needs diagnosing by an engineer.
How much does a freezer icing repair usually cost?
A seal replacement is one of the lower cost refrigeration repairs. A defrost heater, timer or refrigerant fault costs more, and diagnosis time varies by make and model. An engineer can usually confirm the cause on a single visit.
Does freezer icing affect food safety?
Yes. Ice build-up reduces airflow, causes temperature fluctuations and can push cabinet temperature above safe limits. This is a direct HACCP concern and should be logged and acted on under your food safety management system.
Stop the ice before it stops your service
Advantage Catering Equipment is triple-ISO certified (9001, 14001, 45001) and covers commercial refrigeration repair and maintenance right across Kent from our Folkestone base.
📞 Call 01304 873469 Fridge not getting cold?