Why do Air Conditioners Leak Water?

Published on: April 15, 2013

Many homeowners have asked their HVAC professionals, “Why do air conditioners leak water?” Your air conditioning system cools the air in your home partly by extracting moisture from the air. For portable units and window air conditioners, a small amount of water leaking from the unit is normal. However, if you have a central air conditioning system and the unit is leaking a considerable amount water, it is time to call an HVAC technician to have your system inspected and repaired.

Why Do Central Air Conditioners Leak Water?

There are several reasons why a central air conditioning unit may leak water. Some problems are easily remedied and others may require significant AC repairs. Your central air conditioner system will expel a certain amount of water as moisture is removed from the air. Normally, this water is collected in the condensate drain and carried into the plumbing system or outside of the house. If you notice water dripping from the air conditioning unit into a pan or drain, this is normal. However, if your central air conditioner is leaking water on the floor, ceiling or into a wall, the potential for water damage to your home is imminent. This situation is not normal and you need to have an air conditioning contractor inspect your system to discover the issue.

Some reasons why air conditioners may leak water include:

– Improper Portable or Window AC Installation

If your portable or window AC unit is not level, the water that should drain from the unit may not end up outside the home. If the unit was installed at a forward tilt, the condensate water may leak from the system inside your home. To fix this problem, your AC unit needs to be tilted slightly forward so that the water flows freely outside the home.

– Clogged Condensate Drain on a Central Air Conditioner

For central air conditioning systems, a clogged condensate drain can cause water to leak from the system. The drain may become clogged with algae or mold. This is one of the simplest and least expensive air conditioning problems to address. Simply clean out the pipes that drain the water into the drainage system or to the outside. These pipes can be cleaned by flushing with water or vacuuming out the debris. Before cleaning the drain pipes for your system, be sure to turn off the power to the AC unit to avoid accidents. You can also call an AC repair technician to clean the drain pipes for you. If this is the only air conditioning problem you have, the cost of the repair would likely be just the cost of a service call.

– Leaking Drainage Pipes

Another possible reason for excessive water leakage from a central AC unit is a leak in the drainage pipe. If a pipe has been damaged, this can cause a water leak. Any damaged sections of pipe should be replaced as soon as possible.

– Frozen Coil on a Central Air Conditioner

When a central air conditioning unit runs over an extended period during extreme temperatures, especially if air flow is blocked in some way, ice or frost may form on the evaporator coil. When the ice melts, the water may leak onto the floor or into the wall. The first thing you should check is your AC filters. If your filters are clogged, the air flow to your system is blocked and ice may form on the coil. Check the intake registers to make sure that nothing is blocking the air flow into the system.

You should also turn off the unit for a few hours every few days to allow the ice to melt. However, if your system continues to freeze up, call an HVAC technician to diagnose the problem.

– Condensate Pump on a Central Air Conditioner

Many central AC units have a pump that will extract the water from the air conditioner into the drainage system. If this pump fails, water will back up and leak onto the floor or ceiling, or into the walls. A condensate pump is one of those relatively inexpensive AC repairs. Call an air conditioning contractor to diagnose the problem and install a new condensate pump, if needed.

– Tilted Condensate Pan

The condensate pan may not be level, allowing water to leak from the system. Check to see if the pan is level or if something has moved the pan from its original location. If it is out of alignment, move it back to a level position.

Most of the repairs required to resolve a water leak are inexpensive and small. However, if not resolved, these issues may develop into additional air conditioning problems in the future. Water leaks can cause major damage to your home. The potential damage may be much more expensive than the simple repairs that would be required to address the leak. If your air conditioner has developed a significant water leak, take action right away. Call an HVAC technician if you cannot find where the system is leaking. You will benefit by avoiding further damage to your HVAC system and to your home.