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Air conditioning rarely packs up without warning. Weak airflow, a drip from the indoor unit, a rattle you haven't heard before, or a bill that creeps up every summer are all early signs. Catch them then and the repair is usually simpler. Better still, a regular service stops a lot of them happening in the first place.
UK Aircon maintains and repairs air conditioning in homes and commercial premises across the UK. Our engineers are F-Gas qualified, background checked and trained monthly. They work on systems from any manufacturer, including ones we didn't install.
Symptoms and what usually causes them
Most of our call-outs come down to one of the faults below. Each has a handful of likely causes, and working through them methodically means we fix the cause rather than the symptom.
Running but not cooling
If the fan runs but the air is barely cool, look first at the filter, which may be badly blocked. Other common causes are a dirty indoor or outdoor coil, an outdoor fan that has stopped, or low refrigerant from a leak. Low refrigerant always means a leak somewhere. Topping it up without finding the leak just puts off the next breakdown.
Water leaking from the indoor unit
While it's cooling, an indoor unit produces condensate, which should drain away through a pipe or pump. If it's dripping down the wall or onto the floor, the usual culprits are a blocked drain line, a failed condensate pump, a drain pipe without enough fall, or a unit that is not level. Ice forming on the coil and then melting can also overflow the drip tray.
Ice on the coil or pipework
Frost on the indoor coil or the pipe connections points to restricted airflow or low refrigerant. Switch the system off and let it thaw before anyone checks it, because running it iced up can damage the compressor.
New or louder noises
Rattling often means loose panels or worn anti-vibration mounts. Squealing or grinding suggests fan motor bearings. A loud click followed by the system stopping can be an electrical fault or a protection device tripping. Gurgling usually relates to the condensate drain.
Unpleasant smells
A musty or damp smell when the unit starts up is normally mould or bacteria on a dirty coil, fan or drip tray. A burning or electrical smell is another matter. Switch the system off at the isolator and get it inspected before you use it again.
Error codes on the display
Most modern units show a flashing light pattern or code when they detect a fault, such as a sensor failure, a communication error between indoor and outdoor units, or high or low pressure. Codes differ between manufacturers, so jot it down before you ring us. It helps the engineer turn up with the right parts.
Short cycling
If a system keeps switching on and off every few minutes, it's short cycling. It can be down to an oversized system, a faulty thermostat or sensor, a refrigerant problem or an electrical fault. The room never feels quite right, and the constant starting wears out the compressor and wastes energy.
Our blog post on air conditioning repair goes into more detail on cost-effective fixes.
What an air conditioning service involves
A proper service is a structured inspection and clean, and it goes well beyond washing the filters. A typical visit covers:
- Filter clean or replacement
- Indoor coil and fan cleaned
- Outdoor coil cleared of debris
- Condensate drain and pump tested
- Refrigerant pressures checked
- Supply and return temperatures measured
- Electrical connections tightened
- Controls and remote tested
- Mountings and pipe insulation inspected
- Findings recorded and reported
Those readings give us a baseline, so if performance slips gradually between visits we can spot it early. For background, see our blog guide to air conditioning maintenance.
Recommended servicing intervals for homes and businesses
At UK Aircon we recommend once a year as the minimum for most domestic systems, ideally before the warmer months. Commercial systems and anything heavily used, such as restaurant kitchens, busy shops, gyms and server rooms, usually need servicing two or more times a year, and our blog on commercial air conditioning upkeep goes into that side further. Between visits, clean the indoor filters every few weeks when the system is working hard. Regular servicing keeps running costs down too, and our article on how much air conditioning costs to run explains why efficiency falls as coils and filters get dirty.
Legal leak checks under the F-Gas rules
Air conditioning systems containing fluorinated refrigerant at or above 5 tonnes CO2-equivalent must be leak checked at regular intervals by an F-Gas qualified engineer, and the operator must keep records. The interval depends on the size of the refrigerant charge. Plenty of larger commercial and VRF systems are caught by the rules. Small single-room domestic splits are often under the threshold. We can tell you if yours is covered, and for commercial air conditioning sites we can build the checks into a maintenance agreement. Businesses in the North East will find local details on our air conditioning Newcastle page.
Covered by our installation warranty?
Systems installed by UK Aircon carry a 5-year warranty on parts and labour, which includes access to 24-hour emergency call-out, complimentary maintenance check-ups and discounted spares. Keep your service records together with your installation paperwork.
Repair or replace? A practical way to decide
Repair is usually the sensible choice for a fairly young system with a one-off fault and parts still available. Once several of the points below apply, replacement starts to look like the better bet.
| Factor | Points towards repair | Points towards replacement |
|---|---|---|
| Age and condition | Younger system, otherwise in good order | Older system with repeated faults |
| Fault type | Sensor, fan motor, drain or control fault | Compressor failure on an ageing unit |
| Refrigerant | R32 or R410A, gas readily available | R22, which can no longer be used for servicing |
| Performance | Room still reaches temperature after repair | System was undersized or the room use has changed |
| Running costs | Costs stable year to year | Costs rising despite servicing |
You'll get an honest recommendation from us whichever way it goes. If replacement is the right call, see our pages on domestic air conditioning installation or our full services overview.
Older systems still running on R22
R22 used to be the standard refrigerant in air conditioning, but it can no longer be used to service systems. So if an R22 unit springs a leak or needs any work on the refrigerant circuit, it can't be recharged with R22. Some systems can be adapted to take a replacement refrigerant. That often costs you performance and reliability, though, and the equipment is probably near the end of its working life anyway. Most of the time a planned replacement with a modern R32 (or similar) system works out cheaper, and you won't be caught out by a breakdown in the middle of summer. Our engineers will safely recover the refrigerant from the old system.
Checks to try before booking an engineer
Sometimes the explanation is simple. Before you book a visit, check that:
- The remote is set to cool or heat, not fan or dry
- The remote batteries are working
- The filters are clean
- The outdoor unit is not blocked by leaves, bins or furniture
- The isolator and circuit breaker are switched on
Still not right? Switch the system off and get in touch. Please don't take the covers off or try to handle refrigerant yourself. That needs F-Gas qualifications and specialist equipment.
Repair and servicing FAQs
My unit is switched on but the room stays warm. What should I check first?
The most common causes are a blocked filter, dirty coils, a stopped outdoor fan or low refrigerant from a leak. Check and clean the filter first. If cooling does not improve, an engineer should find and repair any leak.
Why is water dripping from my air conditioning unit?
Water leaks from an indoor unit are usually caused by a blocked condensate drain, a failed condensate pump, poor drain pipe fall or an unlevel unit. Ice melting from a frozen coil can also overflow the drip tray.
How often does air conditioning need servicing?
Domestic air conditioning should be serviced at least once a year. Commercial and heavily used systems, such as those in kitchens, shops and server rooms, usually need servicing two or more times a year.
Can an R22 air conditioning system still be repaired?
R22 can no longer be used to service air conditioning systems, so an R22 unit with a refrigerant leak cannot be recharged with R22. Replacement with a modern system is usually the most reliable and economical option.
Do you repair air conditioning brands you did not install?
Yes. UK Aircon engineers service and repair air conditioning from any manufacturer, including split, multi-split, cassette, ducted and VRF systems.
Is an air conditioning leak check a legal requirement?
Leak checks are legally required for systems containing fluorinated refrigerant at or above 5 tonnes CO2-equivalent. They must be carried out by an F-Gas qualified engineer at intervals based on the charge size, with records kept by the operator.