Your air conditioner is leaking water
Almost always the drain, not the refrigerant - and the damage clock starts fast.
Is this an emergency?
You’re probably seeing
- Water pooling around the indoor air handler or furnace cabinet
- A damp or stained patch on the ceiling below an attic unit
- Water dripping from a vent or from the ceiling register
- The condensate pan visibly full, or overflowing when the system runs
- A musty smell near the indoor unit or in the supply air
What it probably is
A clogged condensate drain line
By far the most common causeThe drain pan is full and the water is spilling over the edge rather than running out. Algae and dust sludge build up in the line over a season.
A dirty filter freezing the evaporator coil
Common - and the filter is yours to fixYou can see ice on the coil or the copper line. When it thaws it produces far more water than the pan can handle at once.
A rusted or cracked drain pan
Common on older systemsThe line is clear and draining, but water still appears underneath. On a system past about fifteen years the secondary pan is a common rust point.
A failed condensate pump
Common where a pump is fittedApplies where the unit sits below the drain line, usually a basement. The pump is silent and the reservoir is full.
A disconnected or poorly sloped drain line
Less common, but easy to confirm visuallyWater appears near a joint rather than at the unit, often after recent work. The line needs a continuous fall to drain.
Low refrigerant from a leak
Less common - and a different repair entirelyIce on the line, cooling that has faded over weeks, and a system that cooled worse each summer. The water is a symptom of the freezing, not the fault.
What to do before anyone arrives
Turn the system off at the thermostat
Set it to OFF, not just up a few degrees. The unit will keep making condensate for as long as it runs, and every additional hour is more water into the ceiling or the floor.
Get the standing water up now, not later
Towels, a wet vacuum, and airflow across the damp area. The EPA advises that wet buildings and furnishings must be dried within 24 to 48 hours in order to avoid mould growth, so this is a same-day job even if the repair is not.
If water has been sitting in a ceiling cavity or under flooring for more than a couple of days, the drying is its own job - treat it as water damage, not as a mopping-up.
Look at the drain pan under the indoor unit
A pan full to the brim with the drain line attached tells you the line is blocked. A dry pan with water elsewhere points at the line, a joint, or the pan itself.
Check the filter and look for ice
A clogged filter freezes the coil, and the meltwater overwhelms the pan. If you find ice, leave the system off and set the fan to ON to thaw it, which can take several hours.
Do not chip or melt the ice. Running a system with a frozen coil can damage the compressor.
If there is a condensate pump, check it has power and is not full
Pumps are usually on a plug or a nearby outlet, and a tripped GFCI is a common and free fix. A reservoir full to the top with the pump silent means the pump has failed.
Call for the drain clear, and mention the ceiling if one is involved
Clearing a condensate line is routine work and inexpensive relative to what it prevents. If the water reached a ceiling, a floor or a wall cavity, say so when you book - that may need a second trade.
This is the end of the homeowner sequence. Do not attempt to flush a drain line with compressed air into a live system, and do not open the coil cabinet.
What it costs to fix
Ranges below are for the repair itself. For full replacement pricing see the hvac cost guides.
| What it is | What the part costs | What decides your bill |
|---|---|---|
| New air filter | A few dollars | Nothing - this one is yours |
| Condensate drain clear | No part in most cases | Almost entirely the visit and the labour |
| Condensate pump replacement | A modest part | The part plus a short labour job |
| Drain pan replacement | A modest part, but access is the issue | How buried the pan is - an attic air handler is a different job from a basement one |
| Water damage to ceiling or floor | Not an HVAC cost at all | How long the water sat. This is usually the expensive part of the whole event |
U.S. Bureau of Labor Statistics, Occupational Outlook Handbook (May 2025 wage data).
The pattern worth understanding here is that the HVAC repair is usually the cheap half. A blocked drain is a routine visit; a ceiling that has been wet for a fortnight is a different trade and a much larger bill. That is the entire argument for acting the day you notice it. Labour anchor: the national median wage for HVAC mechanics and installers is $29.33 an hour (BLS, May 2025), billed on top of a diagnostic call.
Can I fix this myself?
Water and electricity share a cabinet here. Kill power at the breaker before reaching around the indoor unit or a condensate pump, and do not stand in standing water to do it. If water has reached a light fitting, a ceiling cavity or an electrical panel, stop and get an electrician involved as well.
Reasonable to DIY
- Switching the system off at the thermostat
- Removing standing water and drying the area
- Replacing the air filter
- Checking a condensate pump for a tripped outlet
- Emptying an accessible overflow pan
Call a pro
- Clearing a blocked condensate line properly
- Replacing a drain pan or a condensate pump
- Anything requiring the evaporator coil cabinet to be opened
- Diagnosing a refrigerant leak behind a frozen coil
- Drying out a ceiling, wall or floor that has been wet for days
Your job is to stop the water and dry what is already wet - both of which matter more than the repair itself and neither of which needs a technician. The repair, in most cases, is a short inexpensive visit to clear a drain line. The reason not to postpone it is not the air conditioner, it is the ceiling underneath it.
Is this covered by insurance?
Whether a claim is worth filing depends on the cause, your deductible and how the damage happened - not on the repair price alone.
Sources
Sources last checked
- Mold Course Chapter 2: Why and Where Mold Grows - 24 to 48 hour guidanceU.S. Environmental Protection AgencyRetrieved 2026-09-14
- Heating, Air Conditioning, and Refrigeration Mechanics and Installers - median pay, May 2025U.S. Bureau of Labor Statistics, Occupational Outlook HandbookRetrieved 2026-09-14
Sources for the figures and the legal requirements cited on this page.
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