A cold room is usually noticed a bit too late. Everything seemed fine earlier. The cold room was holding temperature, stock was safe, no alarms, no obvious signs of trouble. Then someone walks in and pauses.

“It doesn’t feel right in here.”

You check the display. The temperature is higher than it should be. Not massively at first — just enough to raise concern. But give it another hour, and it’s climbing.

Now it’s a problem.

A cold room working normally and then suddenly getting warm is one of the most frustrating faults to deal with because it feels unpredictable. One minute, everything is stable; the next, you’re dealing with potential stock loss, disruption, and pressure to act quickly. The key thing to understand is this: systems don’t usually fail without reason. When a cold room temperature rises suddenly, something has changed — either mechanically, electrically, or in the way the system is operating.

When It Happens Suddenly, Start Thinking About What Changed

If the cold room has been running fine and then quickly starts warming up, the cause is often linked to something that’s just happened.

Power issues are one of the first things to consider. A brief interruption in supply, even a small one, can stop the system from running properly. In some cases, the unit may not restart automatically, leaving the room to slowly warm without anyone noticing straight away.

Then there’s the compressor — the part of the system responsible for actually doing the cooling. If that stops working, even briefly, the temperature inside the cold room begins to rise quite quickly. From the outside, the system might still look like it’s running, but without proper cooling taking place.

Another common situation is airflow being affected. If fans stop working or become restricted, cold air isn’t circulated properly. You might find certain areas of the cold room getting warmer faster than others, even though the system itself hasn’t completely shut down.

The Hidden Culprit: Condensate and Safety Shut-Offs

One issue that catches a lot of people out is condensate build-up.

Cold rooms naturally produce moisture as part of the cooling process. That water needs somewhere to go. If the drainage system becomes blocked, or a pump fails, the system may shut itself down to prevent water damage.

From your point of view, it looks like the cold room has simply stopped cooling. But in reality, the system has done exactly what it’s designed to do — protect itself.

It’s a small component causing a much bigger problem.

Why It Often Feels So Sudden

In truth, many of these faults don’t appear instantly. They build quietly in the background.

• A filter gradually becomes blocked.
• A component starts to wear out.
• A system begins to struggle under load.

But you don’t notice it until the point where performance drops enough to affect temperature.

That’s why it feels sudden — even though the issue has been developing over time.

When the Cold Room Starts Warming, Time Matters

Once the temperature begins to rise, the focus shifts quickly.

It’s no longer just about the system — it’s about what’s inside it.

Food, stock, and temperature-sensitive goods all have limits. The longer the cold room stays above its set temperature, the greater the risk.

In busy environments like restaurants, commercial kitchens, or storage facilities, this can escalate quickly. What starts as a technical issue becomes a business problem within hours.

What You Can Do Straight Away

If you notice your cold room getting warm, there are a few practical steps you can take while arranging a proper fix. Keep the door closed as much as possible. Every time it’s opened, warm air enters and makes the situation worse. It sounds simple, but it makes a real difference.

Avoid adding new stock to the room. Introducing warmer items increases the internal load and pushes the temperature higher. If possible, check whether the system is actually running. Listen for the outdoor unit, check the controller, and see if anything looks obviously out of place.

But beyond that, it’s about acting quickly rather than guessing.

When It Needs an Engineer

If the cold room temperature is rising and not recovering, it’s time to get it looked at properly.

These systems are designed to maintain stable conditions. When they can’t, there’s always a reason — and it’s rarely something that resolves itself.

Delaying the call often makes things worse, not better.

Stopping It from Happening Again

Most situations like this come down to one thing: lack of routine attention.

Cold rooms work hard. They run for long hours, often without interruption. Over time, small issues develop — and without maintenance, they eventually show up as bigger faults.

Regular checks help prevent:

• Blocked drainage systems
• Airflow restrictions
• Component wear is going unnoticed
• Sudden shutdowns

It’s not about overcomplicating things. It’s about keeping the system in a condition where it can do its job reliably. A cold room doesn’t just stop working for no reason. When it goes from holding temperature to getting warm, it’s a sign that something has shifted — and that shift needs attention. The sooner it’s understood, the easier it is to fix. Leave it too long, and it becomes something else entirely.

Need Help Quickly?

If your cold room is getting warm and you need it sorted properly, don’t wait for the situation to escalate.

Call ADK Kooling on 020 3909 9729
We’ll identify the issue and get your cold room back to the temperature it should be.

Air Conditioning usually starts subtly.

No alarms. No obvious failure. Just a quiet moment where something feels… off.

You’re sitting in the office, or walking through your shop floor, and you realise the space isn’t cooling the way it should. The air conditioning is running — you can hear it — but the air coming out doesn’t feel cool. Give it a few minutes, you think. It’ll settle. It doesn’t. Instead, the room gets warmer. Staff start noticing. Someone adjusts the controller. Someone else says it’s been like this all morning. And suddenly, what felt like a minor issue turns into a proper problem.

Air conditioning blowing warm air is one of those faults that catches people off guard because the system looks like it’s working. It hasn’t stopped. It hasn’t gone silent. It’s just… not doing its job. And that’s where the confusion begins. The first thing to understand is this: air conditioning doesn’t “create cold air” — it removes heat. If warm air is coming through, it usually means that heat isn’t being removed properly somewhere in the system.

In most cases, the issue sits outside, not inside. The indoor unit is simply pushing air into the room. The real work — the part that actually cools — happens at the outdoor unit. If that stops working, even partially, you’re left with a system that runs but doesn’t cool. We see this all the time. The indoor unit is on, airflow feels normal, but step outside, and the external unit is silent. No fan, no compressor, nothing. At that point, the system isn’t cooling — it’s just circulating air.

Sometimes it’s something simple, like a power issue. A breaker may have tripped, or the supply has dropped out without anyone noticing. Other times, it’s a fault that’s forced the system to shut itself down for protection. Either way, the result is the same: warm air indoors, rising temperature, and growing frustration. Then there are the slower faults — the ones that build quietly over time.

A system might still cool slightly, but not enough. You might notice it taking longer to bring the temperature down or struggling during warmer parts of the day. Eventually, that slight drop in performance becomes obvious. The air no longer feels cool at all. This is often where refrigerant comes into the picture.

If levels are low, the system can’t absorb heat properly. It keeps running, keeps trying, but never quite gets there. From the outside, it looks like it’s working harder than usual — longer run times, less result. It’s not a sudden failure. It’s a gradual decline. And by the time it becomes noticeable, it usually needs proper attention.

Another common cause is far less technical, but just as impactful.

Filters.

It’s one of those things that gets overlooked because it doesn’t feel urgent. But when airflow is restricted, the system can’t operate properly. It overheats, struggles, and in some cases, starts protecting itself by reducing performance.

What you feel indoors is warm, weak air — even though the system is technically still running. It’s a small issue that turns into a bigger one simply because it’s left too long. Of course, there are also the more serious faults — the ones that don’t resolve themselves and don’t improve with basic checks.

The compressor, for example, is central to the entire cooling process. If it isn’t working properly, the system cannot do what it’s designed to do. You might still get airflow, you might still hear the unit running, but without that core function, cooling simply doesn’t happen.

These are the situations where guessing doesn’t help. The system needs to be checked properly, with the right tools and experience. What makes this issue particularly frustrating is how misleading it is. If a system stops completely, it’s clear something’s wrong. You call someone, get it fixed, move on.

But when air conditioning is blowing warm air, it sits in that grey area. It feels like it should be working. It almost works. And that delay — that hesitation — often means the problem is left longer than it should be.

Meanwhile, the environment keeps getting warmer. In commercial spaces, that matters more than people realise. It’s not just about comfort. It’s about how the space functions.

An office that’s too warm affects concentration. A retail space that feels uncomfortable affects how long customers stay. In more sensitive environments, like server rooms or storage areas, rising temperatures can lead to far more serious consequences.

What starts as a mild inconvenience can quickly turn into disruption. So what should you do when it happens? Start simple. Check the obvious things — settings, power, and whether the outdoor unit is running. Sometimes, the answer is straightforward. But if everything appears normal and the system still isn’t cooling, it’s time to act properly.

Because systems don’t fix themselves. And running a faulty air conditioning system often makes things worse, not better. The truth is, most of these issues are preventable.

Regular maintenance catches problems early. Filters get changed before they block airflow. Refrigerant levels are checked before performance drops. Components are monitored before they fail. It’s not about avoiding every issue — that’s unrealistic. But it’s about avoiding the kind that show up at the worst possible time. Because they always do.

And that’s usually how these situations end. Not with a dramatic breakdown, but with a gradual realisation that something isn’t right — followed by a decision to deal with it properly.

The sooner that happens, the easier the fix.

Need It Sorted Quickly?

If your air conditioning is blowing warm air and the space is getting uncomfortable, it’s worth getting it checked before it turns into a bigger issue.

Call ADK Kooling on 020 3909 9729 – We’ll find the fault and get your system cooling properly again.

Your phone buzzes at 6:47 AM, and the Server Room AC failed. It’s an alert from the monitoring system: server room temperature 28°C and climbing. The setpoint is 22°C. You pull up the BMS remotely — both AC units are showing offline. By the time you drive to the site, it’ll be 35°C in there. Your servers are heading for thermal shutdown, and every minute counts.

Server room AC failure is a genuine emergency. Unlike a warm office — which is uncomfortable but manageable — a hot server room causes hardware damage, data loss, and business-critical downtime. Servers start throttling performance at 35°C and begin shutting down to protect themselves around 40°C. This post covers what to do right now, what probably caused the failure, and how to prevent it from happening again.

Our engineers see this fault regularly across Canary Wharf. An emergency breakdown service contract catches this kind of issue early, well before it escalates into a costly PPM.

Immediate Steps — Do These Now

Check the electrical supply first. Before assuming both AC units have mechanically failed simultaneously — which is unlikely — check the distribution board serving the server room cooling. A tripped breaker is the single most common reason for both units going down at once. If a breaker has tripped, reset it once. If it trips again immediately, you have an electrical fault — stop resetting and call an electrician.

Open doors for temporary airflow. If the server room has no cooling and the temperature is climbing, open the doors to allow air circulation from the surrounding space. It’s not proper cooling, but it slows the temperature rise. Point portable fans into the room if you have them. You’re buying time, not solving the problem.

Shut down non-critical servers. Every running server generates heat. If you can identify non-essential systems — development environments, test servers, backup jobs, staging platforms — shut them down immediately. Reducing the heat load inside the room directly slows the temperature climb. Focus on keeping production systems alive.

Check the BMS or unit controllers for a reset. Some AC systems lock out after a fault and need a manual reset to restart. Check the unit controllers on each indoor unit or the BMS interface. A power cycle on the controller — switching it off at the isolator, waiting 30 seconds, switching it back on — can sometimes clear a transient fault and get the unit restarting.

Call your AC contractor now. Not after lunch. Not after the morning meeting. If you have a maintenance contract with an emergency response SLA, activate it immediately. Server room temperatures above 35°C cause real damage. You need an engineer on site within hours.

Why Both Units Failed Simultaneously

Most server rooms have redundant cooling — two or more units where any single unit can handle the full heat load alone. So why are both down? The answer is almost always one of these.

Power transient tripping both units. A voltage spike, a supply dip, or a momentary power cut trips both units off their electrical supply simultaneously. Both units share the same distribution board, and when the supply glitches, everything goes. The fix might be as simple as resetting a breaker, but the root cause — a faulty contactor, a compressor drawing excessive starting current, or an upstream supply issue — needs investigating to prevent recurrence.

Condensate pump blocked causing safety shutoff. Precision AC units generate condensate, and most server room installations use a condensate pump to remove it. These pumps have a float switch that shuts down the AC unit if the condensate tray fills up — preventing water damage to the server room floor. If both units have condensate pumps of the same age, they tend to block within weeks of each other. We see this pattern constantly. Same pumps, same environment, same lifespan, same failure window.

Dirty filters on both units. If nobody has changed the filters in six months, both units are labouring with restricted airflow. They run hotter, draw more current, and eventually trip on high pressure or thermal overload. Two neglected units deteriorate at the same rate and fail around the same time. It’s not coincidence — it’s predictable neglect.

One compressor fails, the second unit overloads. If one unit’s compressor dies, the remaining unit has to handle 100% of the cooling load. During peak hours — or if the surviving unit is already in marginal condition — it runs flat out, overheats, and trips on overload protection. Now you have two down units: one with a dead compressor, one with a tripped overload. What started as a single failure cascades into total cooling loss.

The Redundancy You Need

Industry standard for server room cooling is N+1 redundancy. If you need one unit’s worth of cooling capacity to handle the heat load, you install two. Each unit should independently handle the full load. The second unit isn’t backup — it’s your insurance policy for exactly this scenario.

This problem often goes hand in hand with an AC system not cooling the building. If you are noticing both symptoms, it is worth getting an engineer out before the system fails completely. We have also covered Daikin U4 communication faults in a separate guide.

If your server room has two units but both need to run simultaneously to maintain temperature, you don’t have redundancy. You have two units splitting a load that’s too big for either one alone. The next single failure becomes a total cooling loss. We audit server room cooling setups regularly and can tell you within an hour whether your redundancy is genuine or on paper only.

Preventing the Next Emergency

Quarterly filter changes. Annual condensate pump cleaning and testing. Compressor current measurement to catch deterioration early. Refrigerant pressure checks. These are the basic PPM tasks that prevent the faults described above. The things that kill server room AC are almost always preventable with routine maintenance that costs a fraction of an emergency call-out.

Environmental monitoring with instant alerts is non-negotiable. If your server room doesn’t have temperature sensors with email or SMS alerts, fit them today. A sensor that costs less than a round of drinks gives you the early warning that turns a disaster into an inconvenience.

ADK’s Server Room Emergency Response

We offer a 2-hour emergency SLA for server room clients across London. Our engineers carry common spares — contactors, capacitors, condensate pumps, fan motors, filters — and can diagnose and repair most faults on the first visit. For compressor failures requiring parts on order, we deploy temporary portable cooling units to bridge the gap and keep your servers running.

If your server room AC has failed and temperatures are rising, call ADK now on 0208 831 8900. This is what we do.

When a cold room, commercial fridge, or chiller cabinet starts running warm, every minute counts. Food safety, stock value and service levels are at risk, and guesswork can make matters worse. This guide provides safe, practical checks you can carry out quickly to help stabilise temperatures and gather clear information for the engineer.

We outline what to check first, what to record, and when to stop and call an F-Gas certified engineer. We also explain our rapid 6-hour response across London, typical van stock parts, and sensible steps to protect stock while you wait.

If in doubt at any stage, keep doors closed and contact our service desk. The aim is to preserve stock and prevent damage to the system.

Safety first
Before carrying out any checks, ensure staff understand the basics:

• Do not open sealed refrigeration circuits. Refrigerant work must be carried out by an F-Gas certified engineer.
• Take care around moving fans and live electrics. Only isolate power where instructed and where it will not risk a full defrost of a freezer without a plan to protect stock.
• Keep doors closed as much as possible to limit temperature rise.

Quick stabilisation steps
Simple actions can slow temperature increases:

• Minimise door openings. Use a single person for retrievals.
• Consolidate stock into the coldest cabinet or area of a walk-in, leaving space around evaporator fans.
• Use ice packs or frozen gel packs to help maintain temperature in fridges where available.
• Move high-risk items first in line with your HACCP plan, prioritising raw fish, dairy and cooked ready-to-eat foods.

Step-by-step checks you can carry out safely
Work through these in order and record findings with times on your log sheet.

Power supply and isolation switches
Check that the cabinet or condensing unit has power. Inspect local isolators and fused spurs. Has the outdoor unit been switched off during cleaning or deliveries?
Confirm the plug or spur fuse has not blown. Do not increase fuse ratings.
If the controller is blank, attempt a controlled power cycle once at the isolator and note the time and any fault codes on restart.

Door seals, hinges and closing
Carry out a paper test: close a sheet of paper in the door and pull. If it slips out easily at multiple points, the gasket may be worn or the door misaligned.
Check for split or flattened seals, damaged hinges or poor alignment preventing full closure.
Listen for door alarms and ensure the door latches properly.

Airflow and product stacking
Inside: ensure nothing blocks evaporator inlets or outlets. Leave at least a hand’s width clearance around fan guards.
Outside: check the condenser has at least 300 mm of clear space and is not obstructed by boxes, linen or stock. Poor airflow increases pressure and raises temperatures.

Condenser cleanliness (external or undercounter)
Look for dust, flour or grease build-up on condenser fins. If safe, gently brush or vacuum along the fin direction. Do not use sharp tools or pressure washers.
Kitchen environments often require monthly light cleaning and periodic deep cleaning.

Evaporator condition and defrost
If visible, check for heavy frost or ice build-up. Ice bridging fins or covering fan hubs indicates a defrost or airflow issue.
Trigger a manual defrost from the controller if your HACCP plan allows and stock is protected. Do not chip ice away.
Ensure defrost cycles are appropriate for operating hours and load.

Drain and tray blockages
Check the condensate tray and drain line. Standing water, debris or overflow can refreeze and restrict airflow.
Clear visible debris at the inlet. If blocked further along, record for the engineer.

Temperature probe position and accuracy
Ensure the probe is in free air, not touching surfaces or sitting in water.
If using a product simulation bottle, confirm it is correctly filled and positioned away from the door.
Compare the display reading with a calibrated thermometer and record both.

Fans and operating sounds
Check evaporator fans run when the compressor is operating. Lack of airflow often results in warm conditions despite a cold coil.
Listen at the condensing unit: buzzing without starting, repeated clicking or tripping may indicate component or compressor failure. Stop further restart attempts and call for service.

Stop and call immediately if you find:
Heavy icing on the evaporator, repeated tripping, compressor short cycling, oily residue on pipework (possible refrigerant leak), or burning smells.

When to call an F-Gas certified engineer
Call promptly if you suspect a refrigerant leak, electrical fault, failed fan motor, defrost heater issue or controller fault. These require specialist tools and certified handling. We carry nitrogen for pressure testing, electronic leak detectors, start components, defrost heaters, fan motors and common controllers to maximise first-visit repairs.

What to tell the engineer
Clear information speeds up diagnosis:

• Unit type and location
• Make and model if available
• Symptoms, fault codes and checklist observations
• Latest HACCP temperatures and time since last normal reading
• Any recent cleaning, electrical work or door damage

Temporary steps to protect stock
If temperatures are rising and an engineer is on the way:

• Keep doors closed and lights off to reduce heat load
• Reduce product density near the evaporator to improve airflow
• For walk-ins, place sealed ice packs on upper shelves, away from probes
• Move high-risk items to another working unit or blast chiller where available

Our response and typical van stock
We provide a 6-hour response across London. Our engineers typically carry:

• Start capacitors, relays, fan motors and blades
• Defrost heaters, termination thermostats and drain heaters
• Controllers, door seals, contactors and sensors
• Leak detection equipment, nitrogen, recovery units and F-Gas compliant tools
• Cleaning equipment for condensers and drains

If a specialist part is required, we will source it promptly and advise on safe stock management in the meantime.

Repair or replacement?
As a guide, if repair costs are below around 40% of replacement and the unit is in reasonable condition, repair is often worthwhile. If costs exceed around 60% or the unit is near end of life, replacement may be more economical. We will provide clear options and expected lifespan after repair.

With proper maintenance, a commercial fridge typically lasts 8 to 12 years. Poor airflow, dirty condensers and worn door seals can significantly reduce this.