AC Leaking Water in Sunnyvale

AC Leaking Water in Sunnyvale

An AC that drips water is almost never a dead system. When your evaporator coil pulls heat out of the air, it also pulls moisture, and that water has to drain somewhere. In most Sunnyvale homes that means a condensate line running to a pan, a float switch, and either gravity or a small pump moving it out. When one of those parts clogs, cracks, or quits, the water shows up on a ceiling, a closet floor, or the slab under the furnace. Fix the part, and the leak stops.

Sunnyvale gets warm enough inland in summer that AC here tends to run long stretches rather than short bursts. Longer run times mean more condensate moving through the line every day, and a drain that was barely keeping up will back up sooner under that load. The other Sunnyvale factor is the housing. Plenty of the older single-story ranches keep the air handler in a hall closet or up in the attic, and where additions got tacked on later the equipment often ends up working harder than the original sizing. An attic or closet unit leaks onto something you notice, a bedroom ceiling or drywall, not a garage floor.

These common causes are cheap to find and fix relative to the drywall and ceiling damage they cause if they run for days. We come out, find the actual point of failure, and put the repair and the number on a written estimate before we touch anything.

Common causes

Clogged condensate drain line. The single most common cause. Algae and dust build a plug in the drain line, water backs up into the pan, and it overflows. We clear the line with a wet vac at the termination and flush it, then confirm flow end to end. On a long-run Sunnyvale system we usually recommend a clear trap or an access tee so it can be flushed at the next maintenance instead of clogging blind.

Cracked or rusted-through drain pan. Older attic air handlers often have a primary pan that has corroded through, or a secondary pan full of standing water. We inspect both pans, and if the primary is cracked we replace it. Where the unit sits over a finished ceiling, we also verify the secondary pan and its overflow path are actually doing their job.

Stuck or failed float switch. The safety float is supposed to shut the system off before an overflow reaches your ceiling. When it sticks or its wiring corrodes, the AC keeps running and the pan keeps filling. We test the switch by lifting the float and confirming the unit cuts out, then replace it if it doesn't. On attic units this part is what saves the drywall.

Failed condensate pump. Closet and attic handlers that can't drain by gravity rely on a small condensate pump. When the pump motor burns out or its check valve fails, water has nowhere to go. We test the pump under power, check the float inside it, and replace the unit if it's dead. These are an inexpensive part, but a dead one floods fast.

Frozen coil that thaws and overflows. A dirty filter, low airflow, or low refrigerant can ice up the evaporator coil. The ice melts faster than the drain can carry it and the pan overspills. The water is a symptom here, not the disease. We find out what froze it, whether that's a low charge, restricted airflow, or a failing blower, and fix that cause so it doesn't refreeze.

Disconnected or sloped-wrong drain line. On homes with later additions or DIY HVAC work, we sometimes find a drain line that came loose at a joint or was run nearly level so it never fully drains. We re-seal joints and re-pitch the line to a proper fall so condensate actually leaves the building.

How we diagnose it

• Where the water is actually coming from, whether that's a pan overflow, a line joint, the pump, or the coil, before we assume anything.
• Both the primary and secondary drain pans on attic and closet handlers for cracks, rust, and standing water.
• Flush the condensate line and confirm flow all the way to the exterior termination.
• The float switch under power, and the condensate pump where one is present.
• Filter, coil, and airflow for a freeze-thaw cause, plus refrigerant pressures if the coil shows ice.

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

AC Leaking Water in Sunnyvale: common questions

Nearby and related

AC Leaking Water near Sunnyvale: Mountain View · Santa Clara · Cupertino .

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