Why is my Air Conditioner Leaking Water?

An air conditioner leaking water can be pretty frustrating. Not only are they messy, but they can potentially cause significant water damage to your home. In fact, these “small” inconveniences can sometimes lead to big problems.

Common Causes of AC Water Leakage

The following issues can cause water leaks in your central AC system:

Clogged Drain Line

A clogged condensate drain pipe can make your AC system’s drain pan overflow. This is probably the most frequent cause of water leakage from a central AC system, bringing many service calls to HVAC professionals as summer temperatures rise. Yes, the hotter it gets, the more water collects into the drip pan. Drain lines can become clogged with dirt, rust, algae and other debris.

Disconnected Drain Line

When AC systems are improperly installed drain pipe fittings may not be secure. Over time, they can loosen, causing the drain pipe to disconnect from the AC unit and allowing the condensate to drain through the ceiling or onto the floor. As with a clogged drain line, the location of the leak will depend on whether the primary or secondary drain pipe is the one affected and whether your central AC system is located in the attic or in your house.

Condensate Pump Problems

A malfunctioning or dirty condensate pump can also cause water leakage from your AC system, flooding your attic or basement. Due to the continual presence of water, mold and mildew can grow inside the unit, causing it to clog.

Other Potential Causes of AC Water Leakage

Water leaks can also be caused by the following issues:

• Clogged air filter.
• Low refrigerant.
• Cracked condensate drain pan.
• Evaporator coil could be freezing up.
• Primary drain may be restricted.
• No p-trap and air vent in the drain line to prevent water backup.
• Condensate buildup in un-insulated ductwork.

The first two issues in the list above can contribute to a frozen evaporator coil, which creates its own set of water leakage problems.

Ways to Avoid Damage from Water Leakage

Follow these tips to reduce the likelihood of water leakage issues:

• Make sure your central AC system has a secondary drain line — especially if your air handler is in the attic.
• Install a drain pan overflow shutoff switch, equipped with a float.
• Add a safety pan under your AC unit to catch drain pan overflow.
• Clean or change your HVAC air filter regularly.
• Make sure your ductwork is properly insulated.
• Have your AC refrigerant levels checked regularly.
• Make sure each drain line contains a p-trap and air vent.
• Keep your condensate pump free from mold and mildew by flushing it with a 50% bleach/water solution.
• Schedule annual HVAC maintenance to maximize performance and minimize furnace and AC repairs.

If you have water coming from the registers