A water-dripping AC unit is the single most common emergency call we receive in Dubai, particularly from June through September when every unit in the city is running flat out. The good news: most cases have a simple cause that can be fixed in under an hour. The bad news: if you ignore it, even a small drip can cause thousands of dirhams in damage to walls, ceilings, and flooring — and if you're in an apartment, the apartment below you.
The 4 Most Common Causes
1. Blocked Condensate Drain (Most Common — 80% of Cases)
Your AC unit removes humidity from the air and collects the resulting water in a drip tray, which drains away via a small pipe. In Dubai's humidity and dust environment, this drain pipe blocks easily — algae grows in the moisture, dust from the filters accumulates, and within a season the pipe narrows until water backs up and overflows the tray, dripping through your ceiling or down your wall.
This is a standard 30-45 minute job: the technician clears the drain, flushes it, and treats it with an algaecide tablet to slow re-blocking. Cost: AED 150-250. Don't put this off — a blocked drain that overflows repeatedly will saturate the insulation behind your wall and cause mould that costs far more to remediate.
2. Dirty Evaporator Coil
If your AC filter hasn't been cleaned in months (or years), dust bypasses the filter and coats the evaporator coil directly. This insulates the coil, causing it to get colder than normal, which means condensation forms faster than the drain can handle it. The fix is a coil clean, typically done at the same time as the drain flush. A badly blocked coil also reduces cooling efficiency by 15–25%.
3. Low Refrigerant (Ice Forms, Then Melts)
When refrigerant levels drop — usually due to a slow leak at a joint — the evaporator coil gets too cold and ice forms on it. When the unit runs a defrost cycle or you turn it off, that ice melts all at once, overwhelming the drain capacity and causing a sudden heavy drip. If you notice the dripping is intermittent and the unit isn't cooling effectively, low refrigerant is likely. This requires a gas recharge (AED 200–350) but only after the leak is found and sealed — refilling without fixing the leak is a temporary patch that will cost you again within months.
4. Disconnected or Cracked Drain Pipe
In older installations, the condensate drain pipe can separate from its joint, crack, or become partially crushed in the wall cavity. Water then drains inside the wall rather than to the exterior. This is less common but harder to diagnose — if the unit appears to be draining but you're still seeing wall dampness, this is worth checking.
What to Do Right Now
- Turn the unit off. Running a leaking AC unit accelerates the overflow and deepens any water damage.
- Place a towel or bucket under the indoor unit to protect flooring and any furniture below.
- Don't use the unit until it's fixed — especially if it's mounted above electronics, a bed, or directly above another apartment's ceiling.
- Check your filter. If it's visibly clogged with grey dust, that's almost certainly contributing to the problem.
When Is It Urgent?
A dripping AC is urgent if: the unit is positioned above furniture, flooring, or electronics that could be damaged; if water is appearing through the ceiling below (meaning the drip tray has already overflowed into the wall cavity); or if the volume of dripping is heavy (more than a slow drip).
Don't wait for the weekend. Same-day response prevents a AED 250 drain-clear from becoming a AED 5,000 water-damage repair.
Preventive Maintenance
The single most effective prevention is cleaning your AC filter every 4–6 weeks during heavy usage periods (May–September in Dubai). A clean filter dramatically reduces the rate at which dust reaches the coil and drain. Annual professional servicing — including coil clean and drain flush — should be booked every March before the summer starts.