AC deep cleaning on the Costa Blanca

Why your AC smells when you switch it on

It’s one of the most common issues in domestic air conditioning on the Costa Blanca and almost nobody knows why it happens. When you switch the AC on after winter or after several weeks of no use, a damp, mouldy or unpleasant organic smell hits the room and lingers for hours. The cause is biological. The indoor coil condenses moisture every time the unit cools. That permanent moisture, combined with the organic dust that enters through the filters and the moderate inside temperature when off, creates the perfect environment for bacterial and fungal colonies.

The worrying thing isn’t the smell but what it indicates. The volatile compounds those microorganisms produce while growing are respiratory irritants and, in sensitive people or those with allergies, can cause headaches, nasal congestion, throat irritation and worsening asthma. Children and the elderly are particularly sensitive. What you breathe every time the AC is running is that air passing over a colonised coil.

What a deep hygienic clean covers

Professional cleaning is radically different from wiping the louvres or vacuuming the filters. The proper procedure requires fully dismantling the indoor unit. We start by removing the front cover and tray, washed separately with a descaling detergent. Then we reach the centrifugal blower, where biofilm builds up most because air always passes through it. Each blade is cleaned individually with brush and specific product.

The next step is cleaning the coil, the part with thousands of fine fins where the refrigerant runs. We apply a specific AC descaling product, leave it 15-20 minutes depending on dirt level, and rinse with moderate-pressure water while protecting the rest of the unit with plastic so water doesn’t get where it shouldn’t. Right technique needs experience: too much pressure bends the fins and reduces performance, too little doesn’t carry the dirt away.

The condensate tray and drain are cleaned separately with descaling product because they typically have built-up scale. If the drain is partially blocked, we clear it with a flexible hose. Finally, after drying every component, we apply a disinfectant certified for AC use that eliminates residual bacteria and fungi without leaving dangerous chemical residues.

The Costa Blanca factor

AC units on the Costa Blanca foul up significantly faster than in dry inland regions. Three factors combine. First, average relative humidity on the coast sits at 70-75% for most of the year, keeping the coil constantly exposed to condensation. Second, Saharan dust arriving every summer leaves a fine but sticky layer that sticks to fins and traps other contaminants. Third, salt-laden marine air feeds extra organic material onto the filter.

For those reasons, on first-row coastal locations we recommend mandatory annual deep cleaning. Inland areas like Almoradí or Catral, every 18-24 months is usually enough. For holiday rentals with intensive summer use, an additional mid-season clean (July) on top of the May pre-season is worthwhile.

When you notice the result

After a deep clean, perceptible effects appear immediately. The unpleasant smell disappears from the first start-up. The unit recovers 10-25% of original cooling performance (because a clean coil transfers heat better). Electrical consumption drops in proportion to recovered performance. And respiratory symptoms in sensitive people drop noticeably or vanish.

The service runs 2-3 hours per standard indoor unit. For multi-splits with several indoor units, add 1-2 hours per additional unit. We work with protection material on furniture, floors and walls. By the end, the unit and the area are fully clean.