Why Is My AC Leaking Water?

Oct 18th, 2016 | AC Problems

AC water leak

AC leaking is one of the most common problems during hot summer days. If left unchecked, a small leak could cause a great deal of damage, especially if the air handler of a central AC system is installed above a ceiling. It is also one of the most confusing problems for many people. If your AC unit doesn’t use water to operate, why is water dripping from your unit or leaking from your central AC system?

AC units do more than cool your home. They also dehumidify the air inside. The main components in air conditioners are the same as those in freezers. Refrigeration coils contain a chemical called a refrigerant. When the refrigerant passes through a certain part of the coil, it evaporates, pulling heat from the surrounding air. As the air cools, water condenses on the coils. In a properly operating AC unit, the water drains into a pan and flows away.
However, AC units do not always work properly. Whether you have single, window-installed AC units or a central AC system, here are five top reasons why your unit may develop an AC leaking problem.

Common Causes of AC Leaks

AC Leak from Drain Pan

There is a problem with the drain pan. In window AC units, there are internal channels that allow water to flow away from the coils and into the drain pan. In order for the water to flow properly, the unit must be angled down toward the ground outside the window. The inside of the unit must be at least an inch higher than the outside. For central AC systems, the drain pan may be clogged with dirt and/or debris causing the water to back up into the AC unit. In other cases, the drain pan may be cracked or damaged. In this case the drain pan may be repaired with epoxy glue if the cracks are very small. Otherwise, it is a good idea to have the drain pan replaced.

AC Leak from Drain Line

There is a problem with the drain line. For central AC units, the drain pan connects to a drain line which carries the water away from the house. If the drain line is disconnected or broken, the water will back up, overflow the drain pan and leak. This may happen if the PVC fittings connecting the drain line are not cemented properly or have worn out. The drain line may also be clogged by dirt and/or debris.

AC Leak from Airflow issues

There is a problem with airflow because the air filter or refrigeration coils are dirty. If a filter is dirty, then air cannot pass through it and will, over time, freeze. When the warm air is sucked in, the ice will melt and leak out of the AC unit. Likewise, if the refrigeration coils are dirty, airflow is restricted around the coils, evaporation is reduced, and ice forms around the coils. When the ice melts, leakage occurs. It is prudent to clean and/or replace air filters and to inspect and, if necessary, clean the refrigerator coils and cooling fins monthly during the cooling season.

AC Leak from Temperature Differential

There is a problem with the temperature differential. This might happen if the outside temperature is too low, usually below 60 degrees Fahrenheit. In this situation, the AC unit may not be able to dissipate cool air causing it to cycle on and often repeatedly, letting ice form on the coils. For window AC units this may be caused by humid air from outside leaking into the house because the weather stripping or insulation around the window unit is not adequate. Also, if the window AC unit is too big for the room, the unit will cycle on and off, and ice will form.

AC Leak from Internal issues

There is an internal problem with the refrigerant, coils or compressor. If the refrigerant level in the coils are too low it can cause more condensation, creating a serious leaking problem. Likewise, if the coils or compressor are damaged, leakage can occur. In either case, the unit or central AC system must be repaired by an HVAC professional or simply replaced.
In most situations, AC leaking may be avoided by performing proper routine maintenance on your AC unit or system.