AC problems • Troubleshooting guide
AC Leaking Water? What Homeowners Should Check
A puddle under the indoor unit, a stain spreading on the ceiling, or drips from a pipe outside. Here is what is going on and what to do in the next ten minutes.
Or dial (213) 214-0220 — available 24/7.
The short answer
Your air conditioner pulls moisture out of the air every hour it runs, and on a humid Los Angeles day that can be several gallons. All of it is supposed to drip into a pan under the indoor coil and run out through a drain line. When water shows up anywhere else, that path is blocked, broken or overwhelmed.
The most common cause is a clogged condensate drain: algae and dust build up in the line until water backs up and spills over the pan. The next most common is a coil that froze and is now thawing, which dumps far more water than the pan expects. Cracked pans, a disconnected drain fitting and a failed condensate pump make up most of the rest. First, protect the floor and switch the system off if water is anywhere near wiring. Then decide whether it can wait until a weekday visit or needs a call now.
Most common causes
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Clogged condensate drain line
Algae, mold and dust slowly narrow the drain until water backs up into the pan and spills over. In Los Angeles this is the single most common reason for water under the indoor unit.
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Frozen coil thawing
If the coil iced over because of a dirty filter or low refrigerant, the melt water comes faster than the pan can drain and overflows the edges, often onto the furnace below.
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Cracked or rusted drain pan
Older pans corrode or crack. Water finds the crack instead of the drain, especially under a coil that produces a lot of condensate.
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Failed condensate pump
When the indoor unit sits below the drain outlet, a small pump lifts the water out. When it fails or its float sticks, the reservoir overflows.
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Disconnected or sloped drain fitting
Drain lines get knocked during other work or settle over time. A fitting that has come apart, or a line that runs uphill, leaks at the joint.
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Missing or wet insulation on the refrigerant line
The large copper line sweats when its insulation is missing. The drips look like a leak from the unit but come from the line itself.
Safe checks before you call
None of these involve opening the equipment, touching wiring or bypassing a safety switch. If a check needs a tool or a panel removed, it is not on this list on purpose.
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Turn off the system if water is near electrical parts
Set the thermostat to Off. If water is in contact with the furnace, an outlet or wiring, also switch the AC breaker off and leave it off until the technician arrives.
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Contain the water
Put towels or a shallow tray under the drip and move anything stored nearby. Photograph the wet area; the technician will want to see where it started.
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Look at the outdoor drain termination
Outside, the drain line usually ends near the outdoor unit or at a wall. If nothing drips from it while the AC runs on a humid day, the line is probably blocked.
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Check the filter
A filter that is packed with dust is the classic cause of a frozen coil, and a thawing coil is a classic cause of overflow. Note its condition; replace it only if the unit is off and dry.
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Feel for ice on the copper lines
Frost or ice on the larger copper line near the indoor unit tells you the coil froze. Leave the system off so it can thaw and call.
Stop and call if…
How an AC24Repair technician diagnoses this
The technician first finds where the water is actually coming from, because a puddle on the floor can have four different sources within a few inches of each other. They inspect the drain pan, the drain line and its fitting, the condensate pump if there is one, and the insulation on the refrigerant line.
If the line is clogged, they clear it with suction or a flush from the outside end and check that it slopes correctly. If the coil has frozen, they find out why: a filter, a blower problem or low refrigerant. A cracked pan is measured for a replacement. You get a clear description of the cause, the repair and its price before any work begins, and advice on whether the ceiling or floor needs a separate look.
Repairs that may follow the diagnosis
Which one applies, and what it costs, depends on what the technician finds. You hear the price before any work starts.
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Drain line clearing and flushing
The line is cleared from the outside end, flushed, and treated to slow future algae growth. The float switch, if fitted, is checked and reset.
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Drain pan replacement
A cracked or rusted pan is replaced with the correct size for the coil so condensate goes where it should.
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Condensate pump replacement
A failed pump or stuck float is replaced and the discharge line tested under load.
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Frozen-coil root cause repair
Depending on the finding: filter and airflow correction, blower repair, or locating and repairing a refrigerant leak.
Clear pricing before the work starts.
Diagnostic visit fees depend on the time of day. We publish the confirmed diagnostic fees and explain the repair price before work begins.
Help with this across Los Angeles
Technicians come to homes in the San Fernando Valley, West, Central and Northeast Los Angeles.
AC leaking water: questions homeowners ask
Is it normal for an AC to drip water outside?
Yes. A slow, steady drip from the condensate drain outside on a humid day is exactly what should happen. Water indoors is the problem.
Can I run the AC while it is leaking?
If the water is only in the pan area and nowhere near wiring, a short run to stay comfortable is low risk, but every hour adds water. If ice is present or water touches electrical parts, switch it off.
Will my homeowners insurance cover the ceiling damage?
That depends on your policy and we cannot advise on it. We can give you a written description of the cause after the visit, which insurers usually ask for.
Why did it start leaking right after a hot spell?
Long run times on humid days produce far more condensate, which is enough to overwhelm a partly clogged drain that coped fine in spring.
Do you repair the ceiling?
No. We repair the air conditioner and the drain. For drywall or flooring you will need a separate contractor; we will tell you when the leak is fully stopped so that work is not wasted.
Tell us what’s happening. We’ll take it from there.
Call any time. We schedule a technician within 24 hours and explain the price before repair work starts.
Or dial (213) 214-0220 — available 24/7.