Why Is My AC Leaking Water? Here's What's Going On

Water and HVAC systems don't mix. Ever.

If you're finding puddles around your indoor unit, water stains on your ceiling, or dripping near a vent — that's your system waving a red flag. A lot of homeowners see it and think "I'll deal with it later." Later usually means a bigger mess and a bigger bill.

Let me explain what's going on and what to do about it.

Why your AC produces water in the first place

Your air conditioner doesn't just cool your home — it pulls humidity out of the air too. That moisture drips into a drain pan and flows out through a condensate drain line. Simple system. Works great — until something blocks it.

The most common causes

1. Clogged condensate drain line

This is the culprit most of the time. Algae, mold, and debris build up in the drain line over time and block the flow. Water backs up into the drain pan and overflows. Think of it like a clogged kitchen sink — except instead of backing up into your sink, it's backing up into your ceiling or onto your floor. Not fun.

You can try flushing it yourself with a wet/dry vacuum or a cup of distilled white vinegar poured into the drain access point. If that doesn't fix it, call us.

2. Dirty air filter

I know. I bring this up constantly. But it keeps causing problems so I'm going to keep bringing it up.

A clogged filter reduces airflow over the evaporator coil. The coil gets too cold and freezes solid. When it thaws — and it will thaw — all that ice melts at once and the drain pan can't handle it. Water everywhere. Change your filter.

3. Cracked or rusted drain pan

On older systems, the drain pan itself corrodes over time. Water drains right through it instead of down the line. If your system is getting up there in age and you're seeing persistent leaking, the pan may need to be replaced.Good news ios that replacing the pan is a whole lot cheaper tyha replacing the unit.Silver lining?

4. Low refrigerant

Low refrigerant causes the evaporator coil to freeze for the same reason a dirty filter does — not enough heat transfer. If you're also noticing warm air coming from the vents or ice on the outdoor unit, refrigerant is likely part of the problem. That one needs a licensed tech.

What to do right now

If you're seeing active water damage — wet drywall, ceiling stains, water spreading on the floor — turn the system off immediately and call us. Running it makes things worse.

If it's a small amount and you caught it early, check your filter, try flushing the drain line, and keep an eye on it. If it comes back, don't wait. Water damage has a way of turning a $150 service call into a $2,000 remediation project.

We'd rather you call us early.

Federal Heating & Cooling | Nashville, TN | 615-290-0068