The most common call of the summer
With the first serious heatwave of the year come the first calls about air conditioning that is not cooling as it should. In many cases this is not a major compressor fault but one of these six causes, several of which you can check yourself before arranging a visit.
1. Dirty filters
By far the most common cause. The filter in the indoor unit traps dust and airborne particles, and once saturated it drastically reduces the airflow across the cold coil, so the unit cools far less even though everything inside is working normally. You check it by opening the front grille of the indoor unit, no tools needed, and clean it with water and a soft brush, letting it dry before refitting. In properties near the sea the air also carries fine salt particles that settle just like ordinary dust, so in these areas the filter deserves checking rather more often than inland.
2. A blocked outdoor unit
The outdoor unit needs free airflow around it to shed the heat drawn from inside. If it is surrounded by overgrown planting, stacked terrace furniture, or simply covered in dust and grime after the winter, its performance drops noticeably. Leave at least half a metre of clear space around it and clean the outside of the casing.
3. Thermostat set wrongly
Something as simple as leaving the remote in fan mode rather than cooling, or a set temperature too high for what you actually want, generates a lot of unnecessary call-outs. Confirm the operating mode before suspecting a fault. It also helps to check the batteries in the remote: a remote with low batteries sometimes sends a different command from the one shown on its screen, leaving the unit running in a mode nobody selected.
4. Low refrigerant gas
If the unit has gone several years without a service and the cooling has been getting worse gradually rather than suddenly, there is probably a small refrigerant leak slowly reducing its capacity. This one cannot be fixed at home: it needs an engineer with the right equipment to find the leak and recharge with the exact quantity.
5. Undersized for the space
A split designed for a small bedroom, installed in a large living room with plenty of direct sunlight, will never cool as effectively however often it is cleaned or serviced. In coastal properties with large windows this original sizing error is more common than you would think, and there is no fix short of replacing the unit with a more powerful one.
6. Faults built in at installation
Connecting pipework that is too long, badly insulated or full of tight bends can reduce performance from day one — a problem no subsequent servicing resolves, because the origin is the installation itself rather than how the unit has been used since. Spotting it usually means comparing actual performance against the manufacturer's specification, which only an engineer with the right instruments can confirm.
Why it seems to get worse every summer
It is common for a unit that worked reasonably well last year to seem worse each season. The explanation is usually the progressive sum of several of the causes above: a little more dirt in the filter, a little less gas from a slow leak, a little more planting growing beside the outdoor unit. None would be serious on its own, but together they explain why the unit that cooled fine three summers ago is now barely noticeable in the hottest hours of the day.
| Cause | Can you check it yourself? |
|---|---|
| Dirty filters | Yes, a simple clean at home |
| Blocked outdoor unit | Yes, clear the space around it |
| Thermostat set wrongly | Yes, check mode and temperature |
| Low refrigerant gas | No, needs a technician |
| Undersized for the room | No, needs a technical assessment |
| Installation faults | No, needs a specialist survey |
When to stop trying on your own
If after cleaning the filter and clearing the outdoor unit it still will not cool, or if the cooling has been deteriorating gradually over weeks or months, it is time for a technical inspection. An annual service — cleaning the coil, checking gas pressure and inspecting the electrics — normally gets ahead of most of these faults before they appear at the peak of the heat, when demand for engineers across the Vega Baja is also at its highest. In holiday rentals, where the unit barely switches off during the busiest months, this preventive servicing pays off even more, because a breakdown mid-season directly affects the experience of guests already staying. Booking that service in spring, before the heat and the reservations peak, also avoids competing for a slot with every other owner in the area who left it to the last minute.
If you have checked the filters and the outdoor unit and the air conditioning still will not cool properly, Manitas covers the whole Vega Baja and quotes free of charge to diagnose the exact cause.
