Why is My AC Leaking Water?

Water leaks are the most common summer breakdown. Learn the causes and how to fix it quickly.

The Panic of an Indoor Leak in Mid-Summer

It's a classic scene: you are relaxing in your living room on a hot summer day on the Costa del Sol, and suddenly you hear a constant dripping or see a damp patch growing on the wall below your air conditioner. Water leaks are the most common breakdown we attend to during the months of July and August. Although seeing water falling inside your house can be alarming and ruin your paint or wooden floors, the good news is that, in most cases, it doesn't mean your unit is broken forever. Below, we break down the main causes and what you should do.

1. The Number One Culprit: A Clogged Drain Pipe

When the air conditioner cools your room, it extracts moisture from the air. This moisture condenses into water droplets on the cold coil and falls into a drip pan, to then be expelled outside through a drain pipe. Over time, dust, dirt from the filters, and the moisture itself create a sludge or algae that ends up blocking this pipe. Unable to escape, the water overflows the pan and runs down your bedroom wall. The solution is to unblock the pipe, something our technicians do quickly using wet vacuums or pressurized nitrogen. To prevent this, an annual maintenance service is highly recommended before the summer season begins.

2. Low Refrigerant Gas (Coil Freezing)

If your unit is low on refrigerant gas due to a leak, the system pressure drops and the evaporator coil (the indoor part) gets too cold, eventually freezing completely. While the unit is on, a block of ice forms. When you turn it off, all that ice melts rapidly, generating an amount of water that the drain pan cannot handle. If this is your case, you need an air conditioning repair in Marbella not just to remove the ice, but to find the gas leak, seal it, and recharge the unit. A unit that freezes repeatedly can end up damaging the compressor irreversibly.

3. Extremely Dirty Air Filters

If the air filters are blocked by a thick layer of dust, the warm air from the room cannot reach the cold coil. This causes the exact same effect as low gas: the coil freezes and, upon melting, floods the machine. Cleaning the filters every two weeks is the best way to prevent this disaster and maintain good energy efficiency. A clean filter ensures air flows freely, preventing extreme temperature fluctuations inside the unit.

4. Poor Installation or Broken Condensate Pump

If the indoor unit was not installed perfectly level, the water will not flow towards the drain and will end up overflowing. This is usually noticed shortly after the initial installation. On the other hand, in installations where the drain pipe does not have a gravity fall, a small water pump (condensate pump) is installed to push the water up or out. If this electric pump burns out, gets jammed with dirt, or its sensor fails, water will leak immediately. Condensate pumps require periodic maintenance to clean sludge deposits and ensure correct operation.

What to do if your air conditioner is leaking?

First and most importantly: turn off the unit immediately to prevent electrical short circuits and minimize water damage to your wall, skirting boards, or furniture. Disconnect the power from the main electrical panel if possible. Dry the affected area with towels and place a bucket underneath if the dripping continues. Do not attempt to dismantle the machine or force parts if you do not have experience, as you could break the plastic casing or damage the internal electronics.