Refrigeration plant breakdowns in food logistics

It's 2am at a frozen distribution centre. The store should be sitting at minus 23. The display says minus 16 and it's still moving the wrong way. One evaporator is a block of ice. The night shift has twelve trailers to load before six, and the first one is already on the bay.

Your shift engineer is a good sparky. They've never worked on the plant room. The refrigeration contractor's on-call number goes to voicemail.

That's the real problem with refrigeration in food logistics. The plant is specialist, it fails at night, and the stock starts costing you money the minute the temperature moves.

Stock first, then the fault

On a frozen site the clock is set by the product. In England, food sold as quick-frozen must have been kept no warmer than minus 18°C*. There's a limited allowance for brief periods in transport and local distribution, but not warmer than minus 15°C* (Quick-frozen Foodstuffs Regulations, Schedule 2). The same regulations require warehousing and storage to have recording instruments that monitor the air temperature, with records kept for at least a year*.

Those records will show exactly how long the store sat warm. So use the first ten minutes well:

1. Stop putting warm stock or open doors into the problem. Keep rapid roll doors shut between moves.
2. Take a reading of the air and a few product probes, and write the times down.
3. Tell the shift manager and the technical lead what you know and what you don't. They decide what happens to stock. You give them a time.

For chilled stores the limit is different, and our post on protecting product while the chiller's down covers it.

The faults your shift can look at

Plenty of cold store breakdowns aren't deep refrigeration faults at all. A general maintenance engineer can find a lot of them, as long as they stay out of the refrigerant circuit.

• Defrost. An iced evaporator usually means the defrost has failed. Check the defrost heaters, the timer or controller, and the termination sensor. Then check the drain line heater. If the drain's frozen, the meltwater has nowhere to go and the coil ices again.
• Fans. A seized or tripped evaporator fan looks like a refrigeration fault from the office. It's an electrical one.
• Doors. A door that won't close, a torn curtain or a dead frame heater lets warm, wet air in all shift. That's how you get ice on the coil in the first place. Our rapid roll door guide has the checks.
• The condenser. Fans running and the coil clean? A high pressure trip on the condensing unit is often an airflow problem.

Anything beyond that is a job for a refrigeration engineer.

The plant room is a different job

Many large cold stores run on ammonia. HSE's warehousing guide is blunt about it. It says the greatest hazard comes from the release of ammonia, which "is a toxic and flammable gas". It adds that people shouldn't try to deal with a leak unless competent and authorised to do so, and only in the correct PPE (HSE, HSG76). If the plant room alarm is going, nobody walks in to have a look.

On HFC systems the rule is about qualifications. Working on F gas equipment without the right certificate is against the law (GOV.UK), and our post on F gas certification explains the categories.

Big systems also carry leak check duties based on how much gas they hold, measured in tonnes of CO2 equivalent. GOV.UK lists checks at least every 12 months from 5 tonnes*, every 6 months from 50 tonnes*, and every 3 months from 500 tonnes*. At 500 tonnes and above you must also have a leak detection system (GOV.UK, leak checks). If your store keeps losing gas and nobody has the leak check records, that's a conversation to have on a quiet day.

Nobody goes in alone

At 2am the person fixing the fault is often the only engineer on site. In a freezer, that's a risk in itself.

HSE's guidance on cold stores calls accidental lock-in a serious hazard that can lead to fatal accidents. It says that below minus 12°C*, lone working should be avoided and a buddy system used (HSG76). It also recommends a trapped person alarm, mains powered with battery back-up. HSE's food industry pages add that walk-in chillers and freezers need doors that open from the inside, and that in blast freezers down to minus 30°C, no PPE alone will be enough (HSE, chilled and frozen food).

So if your engineer has to work on an evaporator in the store, someone goes with them. Test the trapped person alarm before they go in, not after. Our post on lone working on nights covers the rest.

What a late engineer really costs

Here's our view. In food logistics, a refrigeration breakdown costs you three ways at once. You risk the stock. You miss trailer slots, and the customer's own delivery windows go with them. And you pay your night shift to stand and wait. Our post on late trailers and missed slots shows how quickly that adds up.

Most sites have a refrigeration contract. Fewer have read what it says about night response. "Four hours" from a call at 2am is 6am, which is when your first wave of trailers is meant to have gone. If the stock is out of limits by then, you've already lost.

That's why we'd split the work. Your own engineers, or a cover engineer, handle the defrost, fan, door and electrical faults straight away. The refrigeration specialist handles the gas side. If your night engineer can't do the first half, you don't have night cover for your cold store. You have a phone number.

What to do on Monday

1. Read your refrigeration contract's night response time, and test the on-call number at 2am one night this month.
2. Write a first check list for defrost, fans, doors and the condensing unit, and mark the refrigerant circuit and plant room as off limits.
3. Test every trapped person alarm in the cold stores, and agree the buddy rule for engineers working below minus 12.
4. Ask your F gas contractor for the leak check records for each system.

* Frozen food temperatures, record-keeping period, F gas leak check thresholds and the HSE lone working temperature correct as of 3 November 2026. Check the Quick-frozen Foodstuffs Regulations on legislation.gov.uk, GOV.UK's leak check guidance and HSE's HSG76 (second edition, 2007) for the latest.