It's August, it's 35°C in Torrevieja or Orihuela Costa, and your air conditioning is blowing air that barely feels cool. Before assuming you need a whole new unit, work through these seven causes — some take minutes to fix, others need a technician.
1. Dirty filters
By far the most common cause. A filter clogged with dust drastically reduces airflow, forcing the unit to work harder for less cooling. During peak season (July and August) we recommend cleaning filters every 15-20 days. It's the first thing we'd suggest checking yourself before calling us — in many cases it solves the problem without needing a visit.
2. Low refrigerant gas (a leak)
If the unit blows lukewarm air instead of cold, and the filters are clean, it's very likely lost refrigerant charge through a small leak. This isn't fixed by simply topping up the gas: the leak needs to be found and repaired first, or the problem will return within months. This is where you need a technician with gauges and a leak detector.
3. Dirty or obstructed outdoor unit
The outdoor unit needs air to flow freely through its fins to dissipate heat. Accumulated dust, leaves, poor positioning (too close to a wall or inside an enclosed space, for example) or, in coastal areas, salt-air corrosion, all gradually reduce its efficiency. See our guide on salt-air corrosion in coastal properties if your home is near the sea.
4. Unit undersized for the room
If the unit was installed years ago, it may have been sized using different criteria, or simply been "whatever was available" without matching the power to the real m². An undersized unit will never bring the temperature down on the hottest days, no matter how well it's running mechanically. We check this during the technical visit by calculating the real heat load of your room.
5. Wrong mode or temperature setting
It sounds obvious, but it's more common than you'd think: the remote might be set to "fan" or "dehumidify" mode instead of "cool", or the set temperature might be higher than you think. Check the mode first, especially if several people in the household use the same remote.
6. Blocked condensate drain
Some units have a safety feature that reduces or stops cooling if the condensate drain is blocked, to prevent water overflowing inside the property. If you also notice dripping or damp stains under the indoor unit, this is almost certainly the cause.
7. Old unit with the compressor nearing the end of its life
A compressor has a limited working life, and after a certain point (especially in units with more than 10-12 years of heavy use) it starts losing capacity gradually, even if the rest of the system is in good condition. If you've already ruled out the causes above and it's still not cooling well, that's a sign the unit may be reaching the end of its useful life.
What you can check yourself vs. when to call a technician
- You can check yourself: dirty filters, wrong mode or temperature setting, visible obstructions on the outdoor unit (leaves, surface dirt).
- You need a technician: suspected gas leak, new noises, a blocked drain with damp stains, or a unit that still won't cool after cleaning filters and checking the mode.
If you've checked the basics and the problem continues, don't wait until the unit stops working altogether in the middle of August — the sooner a leak or mechanical fault is caught, the simpler (and cheaper) the repair usually is.
Other warning signs worth watching
Besides poor cooling, there are secondary signs that often go along with these seven causes and are worth noting before you call us, since they help us diagnose faster over the phone: an odd smell when the unit switches on (possible moisture or mould build-up in the filter), a cycle of switching on and off more often than usual (which can point to a faulty internal thermostat or a low gas charge), or visible ice on the indoor unit or on the outdoor unit's pipework, which almost always points to low gas or a very dirty filter restricting airflow. Tell us what you've noticed when you book — the more detail you give us, the more targeted the first visit will be.
How to stop it happening again
Most of these seven causes are prevented with annual maintenance: cleaning filters and the outdoor unit, checking the gas charge and inspecting the drain before the hot season starts. Booking that service in spring, before the first real heatwave, also means you're not competing for an appointment with everyone else discovering a broken unit in August. We cover this in detail in our preventive maintenance and cleaning service.