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Why Is My Wall Mounted Air Conditioner Leaking Water?

Young Happy Woman Holding Remote Control Air Conditioner In House

Are you worried that your wall-mounted air conditioning unit is leaking water? Seeing a puddle of water around your indoor unit can be alarming and need your immediate attention.

Aircon systems are an essential part of households. They help regulate the house’s temperature and improve air quality.

If you notice a leak, it might signal that something has gone wrong with your unit, affecting its performance.

This article will examine why your wall-mount AC is leaking water and what you should do to solve the issue.


If your wall-mounted AC unit leaks water, it might be caused by a clogged drain pipe, low refrigerant level, or dirty air filters.

Likewise, a rusted or corroded drain pan, faulty condensate pump, or a loose drain connection can also be the issue.

Did you know regular maintenance can help avoid most issues with your climate control device? Call an HVAC repair professional to check your AC and ensure everything works correctly.

Why Does an Air Conditioner Drain Water

Wall With Mold Stain Due To Air Conditioner Leakage.

Except for cooling, an AC also acts as a dehumidifying appliance.

ACs like the HVAC, central ACs, and split AC have a wall-mounted and outdoor unit. The indoor unit houses the evaporator coils responsible for removing heat and moisture from the air.

In most cases, warm air has high humidity. As the air passes through the evaporator coils, it is cooled down, and the excess moisture condenses on the coils. The water droplets drip down into the drain pan for collection.

The water is pushed into the condensate pipe when the drain pan fills up. The tube then redirects the water outside the house for disposal.

However, if this intricate system is disturbed, you might have water leaks around your home. Leaking water can cause water damage and mold growth, ruining the house’s walls and foundation.

6 Reasons Why Your Air Conditioner Is Leaking Water

Seeing water dripping from the drain pipe outlet outside your house is expected.

However, if your indoor unit is leaking water, you should shut off the AC and call a repair expert to assess the issue and prevent some expensive repairs.

Several reasons might cause your wall-mounted split AC to leak. Let us look at some problems that might cause the drainage issue:

1. Clogged Condensate Pipe

Technician Service Removing Air Filter Of The Air Conditioner For Cleaning

The most common reason for your aircon leaking is a clogged drain pipe. During dehumidification, dirt and dust on the evaporator coils can easily dislodge and collect into the drain pan.

Over time, the debris can accumulate and clog the condensate pipe as the water empties.

The blocked line restricts water draining outside the house. The water gets backed up and collects in the drain pan, where it can spill out and start leaking from the wall-mounted unit.

Some modern aircon devices have an electrical sensor that detects when the condensate pan is full. The sensor cuts off power to the unit, preventing the water from leaking and damaging the AC or the house.

How To Clean a Clogged Drain Pipe

Here is a simple procedure to help clean clogged condensate lines:

  • Shut down the AC unit at the circuit breaker. You can find the circuit breaker that controls the unit labeled in the electrical panel.
  • Locate the drain pipe and check if it is blocked.
  • Disconnect the line from the drain valve at the back of the aircon unit.
  • Take an extra-long and flexible cleaning brush and scrub the debris out of the pipe.
  • Use a wet/dry vacuum cleaner to suck up all the debris.
  • You can also flush the pipe using warm water and ensure water flows out the other end.
Damaged Drain Pipe

If the condensate line is too clogged or damaged, we recommend replacing it. This will ensure that the unit properly drains water outside the house.

2. Low Refrigerant Level

Refrigerator Pressure Gauges

In addition, leaking refrigerant fluid can cause drainage issues in your wall-mounted aircon device. During the cooling cycle, the refrigerant travels to the evaporator, which removes heat from the air.

However, the low-pressure level can affect the AC’s performance if you have a refrigerant leak.

The unit does not adequately transfer heat around the evaporator coils, causing them to freeze. When the ice starts defrosting, the water drips into the drain pan and overflows.

How To Fix Leaking AC Coolant

A refrigerant leak can be a hazard to your health and that of your unit. The best option is to call a repair technician to assess the severity of the leak and fix the issue.

Additionally, different aircon units use different refrigerants. Some coolants like Freon (R-22) require a certified HVAC professional to purchase and refill your AC device. This is another reason why you should let an expert handle the leaks.

3. Dirty Air Filter


A dirty air filter might also cause water to leak from your indoor unit.

If the air filter is clogged by dirt and debris, it can limit air circulation into the unit. Without warm air melting the frost, the evaporator coils end up frozen.

Cleaning Dirty AC Air Filters

Let us look at how to clean your aircon filters safely:

  • Shut off the AC using the circuit breaker.
  • Gently remove the air filters. Some air conditioners might have multiple filters, so make sure to remove all of them.
  • Take a vacuum cleaner and suck up the dust and dirt.
  • Using a hose, gently run water over the filter and allow it to dry. Please do not use a pressurized cleaner, as it can damage the microfiber material that traps the dirt.
  • Reinstall the air filter back into the indoor unit.

4. Damaged Drain Pan

Hvac Technician Working On A Capacitor Part For Condensing Unit.

Another reason for your leaking wall-mounted HVAC is a damaged drain pan. Over time, rusting can cause corrosion, causing the drain pan to leak water.

Replacing a Damaged Condensate Pan

Unfortunately, the best fix for a rusted drain pan is replacing it. Here is a step-by-step guide on how to install a new pan:

  • Shut off the aircon unit using the circuit breaker.
  • Gently remove the front panel in your wall-mounted AC.
  • Locate the drain pan.
  • Detach the drain tube connected to the pan.
  • Gently remove the old pan.
  • Install the new drain pan and connect the drain pipe.
  • Reinstall the AC’s front panel.
Replacing The Drain Pan

Some AC models might have the drain pan located behind delicate parts. If you have a problem finding the pan or removing it, call a repair professional for help.

5. A Faulty Condensate Pump

A Technician Opens Up The Top Hatch Of The Outdoor Compressor Unit Of A Split Type Air Conditioner

A defective condensate pump might also be the culprit. Some indoor units require a condensate pump to push water outside the house.

However, if the pump burns out, water can accumulate in the drain pan, causing leaks in your appliance.

Repairing a Damaged Condensate Pump

Though it might seem like a good DIY project, repairing a faulty pump can be challenging, but you should let a qualified HVAC technician handle the repairs.

They will assess the extent of the damage and either repair or replace the pump.

6. Disconnected Drain Line

The Process Of Clean And Wash The Air Condition With The High Pressure Electric Pump

Lastly, a disconnected drainage connection also causes the unit to leak. A loose connection can be due to improper installation when mounting the indoor system.

Additionally, during the cooling cycle, the drain valve can expand and contract causing it to wear out and loosen the pipe connection.

How To Fix a Disconnected Drain Line

If you think that you have a loose drain line, follow these simple steps:

  • Switch off the unit at the circuit breaker.
  • Go to the back of your indoor unit and locate the drain pipe connection.
  • Inspect the connection by checking for leaks or wiggling the pipe to see if it is loose.
  • Tighten the connection by gently rotating the tube until it is secured to the drain valve.

However, you should call an HVAC expert to replace a damaged drain line.


You should not be too worried if you notice a leak in your split ac indoor unit. You can fix the issue without too much hassle.

However, if you are unsure why the unit is leaking, you should call a repair technician to look at it.

The most common reasons for a leaking wall-mounted AC are a clogged drain pipe and air filter, low refrigerant levels, or a disconnected drain pipe. A damaged condensate pump or drain pan can also be a problem.

Frequently Asked Questions

Why Is My Air Conditioner Blowing Hot Air?

If your air conditioner is blowing warm air, it might have a problem with the following:

  • Low refrigerant levels
  • Dirty evaporator coils
  • Clogged air filters
  • A faulty compressor
  • A clogged condensate pipe

Is It OK To Use an AC When Water Is Leaking?

Though your air conditioner can continue to function when leaking water, we do not recommend using it. Water can damage the unit and cause a short circuit.

You should turn off the system and call an HVAC professional to identify the cause of the leak.

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