An air handler that is leaking water on the floor may be the result of a few issues. Water is produced as a byproduct of the cooling system and typically drains away from the house through a hose or pipe. A malfunction anywhere in this system can cause an air handler to not dispose of water properly and result in water overflowing onto the floor. There are a few common issues to consider.
Your air handler could be leaking water on the floor due to condensation or issues with the condensation pan, condensation drain or condensation pipe.
How Condensation Forms
All water found in the air conditioning system has originated from accumulated condensation. An air conditioner cools by blowing hot indoor air across cold Freon coils. These coils "sweat" the humidity in the air, just as a cold glass of water sweats in a hot room. The more humidity in the air, the more condensation forms. This condensation then drips down into a pan. It then drains from the pan by way of a length of PVC pipe or hose that dumps outside your home.
Malfunctioning Condensation Pan
One common source of water issues in the air handler is a malfunctioning condensation pan. The pan is a delicate mechanism and can easily be disturbed by work being done around the air handler or the odd bump or nudge to the unit. A crack in the pan can also cause it to leak.
Most central air conditioning air handlers have user serviceable condensation pans, so consult the manual and remove the cover on the side of the handler. Examine the pan and ensure it is not bent or tilted in such a way as to cause overflow.
Clogged Condensation Drain
The drain in the condensation pan can become clogged with dirt, mold, grime or debris. This typically happens if the unit has not been serviced in a long time or if you have run your air conditioner without a filter for any appreciable amount of time.
Examine the drain in the center of the pan and use a small piece of wire or pipe cleaner to ream out the first few inches of the drain. Pour some water into the pan and ensure that it is draining properly. Handle regular air conditioner maintenance to prevent problems in the future.
Malfunctioning Condensation Pipe
The pipe that carries condensation from the pan to the outside of your home can break, crack or simply slip off its attachment at the air handler. Additionally, the trap in the pipe, or small elbow that holds water and prevents air and water from flowing back up the drain, can be twisted or damaged. Inspect the length of the pipe and the trap and ensure it is functioning properly and is not twisted or otherwise damaged.
Frozen Evaporator Coils
The evaporator coils in your air conditioner can become frozen, especially if you don't change your air filter regularly. When the air filter gets clogged with dirt and debris, it restricts airflow, which can cause the coils to freeze. This prevents the HVAC system from producing cold air, and the ice can melt, causing the unit to drip water on the floor.
Andrew Leahey has been a writer since 1999, covering topics as varied as technology how-to guides and the politics of genetically modified organisms to African food supplies. He is pursuing his J.D. while renovating an 1887 farmhouse located in the New Jersey Pine Barrens.