The three most common problems are restricted airflow, blocked condensate drainage, and control or sensor faults. Low refrigerant is less common than people assume, and when it does occur it means a leak that must be located rather than topped up.
Check these before calling
- The filters. Remove and look at them. If they are grey and matted, that alone can account for poor cooling, icing and a unit that trips. They rinse in warm water and must be fully dry before refitting.
- The outdoor unit. Clear of leaves, shrubs and obstructions, with air able to move freely in and out.
- The mode and setpoint. Units get knocked onto fan-only or dry mode, or onto heating, more often than anyone admits. Check the display.
- The remote’s batteries. A weak remote sends commands the unit does not receive.
- The electrical supply. Isolator, MCB and RCD. A tripped RCD points at a fault worth investigating rather than simply resetting.
- Whether it is icing up. Visible ice on the indoor coil or on the pipework almost always means restricted airflow or low charge, and running it in that state does harm.
Running a system that is icing up risks liquid refrigerant reaching the compressor, which is the most expensive component in it. Switch to fan-only to defrost it, or switch it off entirely, and find out why the airflow is restricted.
The faults we actually find
| Symptom | Usual cause |
|---|---|
| Cooling poorly, running constantly | Dirty filters or a blocked outdoor coil. If both are clear, low refrigerant charge |
| Water dripping from the indoor unit | Blocked condensate drain, displaced tray, or a failed condensate pump |
| Ice on the indoor coil or pipework | Restricted airflow, or low refrigerant charge |
| Unit runs then trips out | High pressure from a blocked condenser, an electrical fault, or a protection device doing its job |
| No response to the remote | Batteries, remote failure, or the indoor unit’s receiver |
| Musty smell | Biological growth on the coil and in the tray. A cleaning job |
| Noisy outdoor unit | Fan blade damage or imbalance, loose panels, worn bearings, or failed anti-vibration mounts |
| Error code on the display | Note it exactly – manufacturer codes are specific and it narrows the fault immediately |
| Cools one room but not another on a multi-split | Indoor unit fault, or a control or valve problem on that circuit |
Notice that the first two rows – filters and drainage – account for a very large share of all domestic air conditioning call-outs, and both are maintenance rather than repair.
Refrigerant leaks
A refrigeration circuit is sealed. If it is low on refrigerant, refrigerant has escaped, and it will keep escaping. Simply adding more is not a repair – it is an expense that recurs, and it is also not permitted: topping up a system with a known leak without repairing it contravenes the F-Gas requirements.
Leaks are found by pressure testing with nitrogen, by electronic leak detector, by ultraviolet dye where appropriate, and sometimes by bubble solution on accessible joints. The usual locations are flare connections at either end of the pipework – which is why the quality of the original installation matters years later – and occasionally a coil or a damaged section of pipe.
Once repaired, the system is evacuated properly and recharged by weight to the manufacturer’s specified quantity, not by guesswork on pressures. The charge quantity is recorded.
When it is not worth repairing
Split systems generally last well, and most faults are worth fixing. The exceptions:
- Compressor failure on an older unit. The compressor is the most expensive component and on a unit past ten to twelve years, replacement of the whole system is often the better value.
- A leak in the indoor or outdoor coil. Coils are expensive and awkward, and a corroded coil often indicates the rest is going the same way.
- Obsolete refrigerant. Systems using older refrigerants that are no longer readily available are increasingly impractical to maintain – a real and growing consideration as the phase-down progresses. See the refrigerant phase-down.
- A system that was never right. If the unit was undersized, badly sited or poorly installed from the start, repairing it returns you to a system you were never happy with.
We will give you the honest comparison, including the efficiency difference, rather than defaulting to replacement.
Note the error code before you reset it. On air conditioning, the codes are specific and genuinely diagnostic.
Questions we get asked about this
Why is my air conditioning not cooling?
In order of likelihood: dirty filters, a blocked outdoor coil, wrong mode selected, or low refrigerant. The first three you can check yourself in five minutes, and between them they account for most calls.
Water is running down the wall from the indoor unit.
A blocked condensate drain, almost always. Switch the unit off before it does more damage. It is a routine clean and clear, and it is the most common preventable fault there is.
Is a refrigerant top-up a normal maintenance item?
No. A sealed system should never need topping up. If it does, it has a leak, and the leak has to be found and repaired – both because the top-up will otherwise be wasted and because topping up a known leak is not permitted.
My unit keeps tripping the electrics.
Do not keep resetting it. It could be a failing compressor, a motor with a winding fault, water ingress, or a genuine electrical fault. All of them need investigating rather than resetting.
The outdoor unit has got much louder.
Usually fan-related – a damaged or unbalanced blade, debris in the fan, loose panels, or failed anti-vibration mounts. Occasionally a compressor on its way out. Worth looking at early, because noise complaints are harder to fix once a neighbour has been irritated.
Can you repair any make?
We work on the common makes. The constraint on older units is parts availability and refrigerant availability, and we will tell you honestly if either is going to be a problem before you spend anything.
Regulations and standards referenced on this page
- Regulation (EU) No 517/2014 on fluorinated greenhouse gases, as retained and amended in GB law — UK Statute Law Database
- Fluorinated gases (F gases): guidance for operators and engineers — Environment Agency / Defra
What happens when you call
Call and describe it
You speak to an engineer, not a call centre. Most jobs can be narrowed down on the phone.
We look at it properly
A real diagnosis before a price, and a straight answer if it is not worth doing.
A written quote
Itemised, so you can see what you are paying for.
The job, and the paperwork
Certificates where the work needs them, and what will need attention next.
Where we do this work
Across Norwich and the whole of Norfolk. If you are on the edge of the county, call and ask — we will tell you honestly whether we are the right people.
- Norwich
- Wymondham
- Dereham
- Attleborough
- Aylsham
- North Walsham
- Cromer
- Diss
- Loddon
- Long Stratton
- Watton
- King's Lynn
Need this doing?
Call and describe the problem — you will speak to an engineer, not a call centre. Written quotes, no estimates over the phone.