AC Leaking Water in Atherton, CA | Bay Area HVAC Service

AC Leaking Water in Atherton

Your AC makes water every time it runs. The evaporator coil pulls moisture out of the air, that moisture collects in a pan, and it drains away. So a wet spot on a ceiling, or water along a closet wall, doesn't mean the equipment is finished. It means the condensate stopped draining and found another way out: a clogged line, a pan that overflowed or cracked, a pump that quit, or a float switch that should have caught it.

Atherton raises the stakes because of where the equipment lives. A lot of these estates run more than one system, and the air handlers get tucked into attics and mechanical closets serving different wings. When an attic unit's drain clogs, the overflow doesn't land on a garage floor where you'd spot it. It soaks insulation and turns up as a brown ring on a bedroom ceiling, sometimes weeks later. The Peninsula's moderate cooling load means these systems still run long enough in summer to move real volumes of water through those drains.

When a house has several systems, the first job is figuring out which unit is leaking and why. We trace it to the specific air handler, find the part that failed, and put the fix on a written estimate before any work starts.

Common causes

Clogged condensate drain on an attic air handler. The most common leak we find in Atherton estates. The drain line off an attic unit slimes up and overflows into the pan, then through the ceiling below. We clear the line with a wet vac and flush it, confirm free drainage, and check that the secondary drain and pan are functioning as the backup they're supposed to be.

Overflowing or cracked secondary drain pan. Attic handlers sit in an emergency pan for exactly this situation. If that pan has corroded, cracked, or its own drain is plugged, the safety net fails and water reaches the ceiling. We inspect both pans, clear the secondary drain, and replace a cracked pan when needed.

Failed condensate pump. Where an air handler can't drain to a convenient point by gravity, it relies on a condensate pump. A burned-out motor or stuck float means water has nowhere to go. We test the pump by filling its reservoir and replace it if it won't run. It is an inexpensive part relative to the ceiling repair it prevents.

Stuck float safety switch. Every properly installed attic system should have a float switch that cuts the AC when the pan fills. When it sticks open, the system keeps running and floods. We test the switch and replace it if it isn't interrupting the circuit, then verify it actually shuts the unit down.

Frozen evaporator coil shedding water on thaw. A coil that ices over from low charge or restricted airflow dumps far more water than the pan handles once it melts. On multi-zone estates this often ties back to a dirty filter on one rarely-checked system or a refrigerant leak. We read pressures and coil temperature to find the root cause, not mop up the symptom.

Zoning imbalance starving one coil of airflow. On the multi-zone systems common here, a stuck zone damper can choke airflow across one coil enough to freeze it. We check damper operation as part of the diagnosis, because swapping a part without fixing the airflow just freezes the coil again.

How we diagnose it

Identify which of the home's systems is leaking and locate that specific air handler in the attic or closet.
Inspect primary and secondary drain pans and clear both drain lines, confirming each runs free.
Test the float safety switch and the condensate pump to see which protection failed.
Check the filter, blower, and refrigerant charge on the affected system to rule out a frozen coil.
Verify zone damper operation if the system is zoned, since a stuck damper can freeze a single coil.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

AC Leaking Water in Atherton: common questions

We have several systems. Can you handle a leak on a specific one?

Yes. Multi-zone, multi-system estates are routine for us across Atherton and the Peninsula. We trace the leak to the exact air handler causing it rather than guessing, and we cover Atherton from our San Ramon base alongside 39 Bay Area cities. A leak near a finished ceiling is a same-day priority when we have the opening.

How much does a leaking attic unit usually cost to fix?

A clogged drain line or float switch is small, typically $150 to $450. A corroded pan replacement or a failed condensate pump runs higher depending on access. The $75 diagnostic gets credited toward your repair, and you get the number in writing before we touch anything. The expensive part is the ceiling, which is why we want to catch it early.

There's a stain on the ceiling but no water on the floor. Is that the AC?

Often, yes. An attic air handler that overflows soaks insulation and shows up as a ceiling stain below before water ever reaches a floor. That usually means the primary drain is clogged and the secondary pan is catching it, or both are overwhelmed. Have it looked at promptly, because a stain means water is already getting past the first line of defense.

Nearby and related

AC Leaking Water near Atherton: Menlo Park · Palo Alto .

This is usually a ac repair in Atherton job. See our ac repair overview or the Atherton service area.