Condensate Leak in the Attic in Danville

Condensate Leak in the Attic in Danville

Danville summers run hot, so the AC pulls real load and makes real condensate. When the primary drain clogs or a pump fails, the water backs up into the emergency pan, and if that fills it comes through the ceiling under the air handler. We see this enough across Danville that it's on our short list of usual calls.

The fix is almost always one part, not a dead system. In the older ranches around the center of town, the air handler often sits in a tight crawl space or low attic with a long, awkward drain run that collects sludge. In the larger Blackhawk and Tassajara homes, we more often find multi-zone systems where the leak is one zone's air handler and the float wiring takes more tracing to sort out. Different layouts, same short list of failures.

What usually isn't broken is the expensive part. The compressor, the refrigerant charge, and the blower are typically fine. What failed is the drainage hardware: a clogged line, a stuck float, a burned-out pump, or a pan that finally corroded through on an older furnace.

Common causes

Clogged primary condensate line. The most common one in Danville, especially in the older west-side homes where the drain runs long and near-flat through a tight crawl space. Algae and debris choke it and the pan overflows. We clear it with a wet vac and compressed air, flush it, and confirm it drains before we leave.

Float switch not cutting the system. The float switch should shut the AC off when the pan fills, before water touches the ceiling. On older Danville installs it's often missing or failed. We test it by lifting the float to confirm shutoff, and add one where there isn't a working switch.

Failed condensate pump. When the attic or crawl space drain can't run to gravity, a pump lifts the water out, and those fail. We see this on both the older ranches and the multi-zone estates. We test the pump under power, check its float and check valve, and swap it if it's done. We carry common pumps.

Corroded or cracked primary pan. On the older gas furnaces still running in Danville's west-side homes, the metal pan rusts through and water bypasses the drain entirely. We inspect with a light and mirror, and if the pan is gone we price the coil-pull and replacement on the estimate, alongside what a full air handler replacement would cost at that age.

Wrong zone's air handler in a multi-zone home. In Blackhawk and Tassajara multi-zone systems, a leak can come from one zone's air handler while the others run fine, which makes the source less obvious. We isolate which unit is producing the water and trace its specific drain and float wiring rather than guessing.

Flat or sagging drain in a tight crawl space. Danville's older homes leave little room to run a properly sloped line, so installers sometimes ran it flat. Water sits, grows clogs, and overflows. We re-pitch the line or add an access tee so it drains and can be flushed in the future.

How we diagnose it

• Inspect the air handler, primary pan, and emergency pan, and in multi-zone Blackhawk systems isolate which unit is leaking.
• Trace the ceiling stain back to the source at the unit.
• Test the float switch by lifting the float to confirm the system shuts down, and add one if it's missing.
• Clear and flush the primary drain line and verify free flow, paying attention to the long crawl-space runs in older west-side homes.
• Check the condensate pump under power and confirm pan slope and level.

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

Condensate Leak in the Attic in Danville: common questions

Nearby and related

Condensate Leak in the Attic near Danville: San Ramon · Alamo · Blackhawk · Walnut Creek · Pleasanton .

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