ac installationin liwan 2.

The shamal is the north-westerly wind that pushes fine desert dust across the Gulf, most aggressively from late May through August. Its particles are far finer than household dust — fine enough to pass cheap mesh filters and coat the evaporator coil itself. In a bad shamal week, a filter that normally lasts two months loads up in a fortnight, and homes near construction sites see the same effect year-round. The filter is the cheapest part in the system and the cause of the most expensive failures: a blocked one cuts airflow, triggers icing, strains the blower and inflates bills before anything visibly breaks. Washing your return-grille filters monthly in summer is the highest-value maintenance act available to you, and it is free.

What you cannot do yourself is clean what got past the filter. Fine dust bonded to a damp coil turns into a felt-like mat a hose will not shift; it needs a chemical foam wash and, for ducted units, access panels opened above the ceiling. If filters look clean but airflow stays weak and bills creep up, the coil and blower wheel are the usual suspects.

Refrigerant is not fuel. It circulates in a sealed loop and is never consumed, so a unit that needs gas has a leak — full stop. The honest version of a regas visit: find the leak with a detector or nitrogen pressure test, repair it, pull a vacuum on the lines, then weigh in the exact charge printed on the nameplate. The dishonest version is a hose, a cylinder, and see-you-next-summer. If you have paid for top-ups two years running, you have paid twice for one unfixed leak.

The gas itself matters. Older UAE units run R22 — the gas everyone still calls freon — which is being phased out under the Montreal Protocol; imports are restricted and the shrinking supply gets pricier every year, so regassing an old R22 unit can cost a startling share of its remaining value. Most systems from the last decade use R410A, and newer machines increasingly use R32, more efficient but mildly flammable. The gases are not interchangeable: R410A runs at much higher pressures than R22, so you cannot refill an old system with new gas. When a technician says an ageing R22 unit with a leaking coil is not worth repairing, the arithmetic usually supports them.

In August humidity a hard-working unit pulls several litres of water a day out of your air. All of it lands in a shallow pan under the coil and leaves through a narrow drain pipe that runs nearly flat above your ceiling, stays damp all year, and is fed a steady diet of fine dust — perfect conditions for algae and sludge. When it blocks, the pan overflows quietly into the ceiling void, and the first sign is a spreading brown stain or a drip through a light fitting. In apartments there is a twist: the stain on your ceiling is very often the upstairs neighbour's FCU, because drain trays sit in the slab void between floors. Establish whose unit is leaking before paying for repairs.

The fix is undramatic: flush and vacuum the drain line, clean the pan, check the pipe's slope, and drop in a slow-dissolving anti-algae tablet. It is a standard line in a proper service, and at AED 150–300 as a standalone job it is cheap insurance against repainting a ceiling. If a unit has overflowed once, ask about fitting a float switch — a small sensor that shuts the unit down before the pan overflows again.