AC Leaking Water Inside the House? Start With the Drain Line
By Cool Aid Air Conditioning, Edinburg, TX ·Published
Your air conditioner makes water every time it runs. As warm, humid air passes over the cold indoor coil, the moisture in it turns to water, drips into a pan and runs out of the house through a drain line. On a humid Valley afternoon that adds up to a lot of water.
When something interrupts that path, the water ends up where it shouldn't: on the floor of the closet, in the attic insulation or on the ceiling below. Here is what usually causes it, what you can check yourself and when it's time to call.
The Most Common Cause: A Clogged Drain Line
The drain line is a thin pipe, and it stays wet and dark all summer. Gulf humidity keeps it running from spring to fall, and algae and sludge grow inside it. Over a season or two that slime can block the line completely.
Once the line is blocked, the pan under the coil fills up. Many systems have a float switch that shuts the AC off when the water rises, to protect the house. So a clogged drain doesn't always show up as a leak. Sometimes it shows up as an AC that stopped cooling for no clear reason, with the breaker fine and the thermostat set right.
Other Reasons an AC Leaks Water
If the drain is clear and you still see water, these are the next things we check.
- A frozen coil. A dirty filter or low refrigerant can let the indoor coil ice over. When the system shuts off, the ice melts faster than the pan can drain. If you see frost on the copper lines, turn the AC off and let it thaw.
- A cracked or rusted drain pan. Older metal pans rust through, and plastic pans crack with age.
- A drain line that came apart at a fitting, often in the attic where nobody looks.
- A failed condensate pump, on systems that need one to push the water out.
If Your Air Handler Is in the Attic
A lot of Valley homes have the air handler in the attic. Those systems usually have a second, shallow pan under the unit with its own drain that comes out somewhere you can see it, often a short pipe over a window or under the eaves.
That pipe should stay dry. If it's dripping, the main drain is already blocked and the backup is doing its job. Don't wait for the ceiling stain. Call and have the main line cleared while the backup is still holding.
What You Can Do Yourself
Start by turning the system off at the thermostat so it stops making water. Then:
- Check the air filter and change it if it's dirty. A clean filter helps prevent a frozen coil.
- Find where the drain line exits outside. Many homeowners clear a clog by holding a wet/dry vacuum over the end of the line for a minute or two.
- If your drain line has an access cap near the indoor unit, pour in a cup of plain water and watch whether it comes out the other end.
- Mop up and set a fan on any wet drywall or insulation so it can dry.
When to Call
Call if the water comes back after you clear the line, if you see ice on the coil or lines, if the leak is in the attic and you can't reach it safely, or if a ceiling is stained or sagging. A stained ceiling means water has been sitting a while, and wet insulation and drywall can grow mold.
A technician clears the line properly, checks the pan and the float switch, and looks for the reason it clogged or froze in the first place. You get the price before the work starts, and the service call is free when we do the repair. Our hours are weekdays 7 AM to 7 PM, Saturday 8 AM to 2 PM and Sunday 9 AM to 2 PM for scheduled visits. We don't take after hours calls.
A yearly AC check up includes clearing the condensate drain, which is the simplest way to keep this from happening every August.