Condensate Leak in the Attic in Los Gatos

Condensate Leak in the Attic in Los Gatos

Air conditioning produces water. The coil condenses moisture out of the air, it drips into a pan, and a drain line carries it off. When the line clogs, the pan overflows, and on an attic install the water comes down through the ceiling. The first symptom in most Los Gatos homes is a stain, sometimes a soft spot in the drywall, before anyone hears a drip.

Los Gatos housing is all over the map, and these calls cluster in the homes that actually have attic air handlers: the hillside customs and the newer luxury builds running full central HVAC, often multi-zone. A good number of the older downtown homes have no forced air at all, so this isn't their problem. Where it does happen, it's almost always one fixable part: a plugged drain line, a float switch that never cut the system, a worn condensate pump, or a pan that's cracked or sloped wrong.

The hillside microclimate plays into it. A west-facing upper room can call for cooling hard through the afternoon while the rest of the house coasts, so the zone serving it runs long hours and its coil makes condensate steadily. That's the drain that tends to overflow first. The emergency pan and the float switch under the air handler are the last line before drywall, and on a multi-zone home we make sure we're chasing the unit that's actually leaking.

Common causes

Clogged primary condensate line. Biological slime builds inside the drain and blocks it, backing water up into the pan until it overflows. We clear the line with a wet vacuum from the termination, flush it, and run water through the pan to confirm flow. We add a cleanout where the line lacks one so it's serviceable next season.

Float switch that never tripped. The safety float should shut the AC off when water rises in the pan. Stuck, missing, or miswired, it lets the system keep running and overflowing. We lift the float to confirm the unit shuts down, and add one where an attic air handler has no protection.

Failed condensate pump. Where an attic unit sits below its drain exit, a small pump lifts the water out, and the zone serving a hot west-facing room runs that pump hard. A burned motor or stuck float means the reservoir overflows. We power-test the pump, check its check-valve, and replace it if it can't clear its tank reliably.

Cracked or corroded primary pan. An aging pan can crack or rust through and leak straight to the ceiling even with a clear drain. We inspect it with a light and mirror, confirm it holds water, and replace any pan that's failed.

Improper pan slope at install. An air handler set dead level or tipped the wrong way lets water pool in a corner and spill instead of draining. We check the pan's pitch and shim the unit so it runs to the fitting, and verify the drain keeps a downhill slope its whole length.

Chasing the wrong zone's air handler. On a multi-zone hillside home it's easy to assume the leak is the nearest unit. We trace the water back to the air handler actually overflowing, usually the one serving the hardest-working zone, instead of servicing the wrong one.

How we diagnose it

• On a multi-zone home, confirm which air handler is overflowing before opening anything.
• Pour water through the primary pan to tell a clog apart from a cracked or mis-sloped pan.
• Test the float switch by lifting the float and confirming the system shuts off.
• Clear and flush the primary drain line and verify flow at the termination.
• Check the condensate pump under power and inspect both pans for standing water.

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

Condensate Leak in the Attic in Los Gatos: common questions

Nearby and related

Condensate Leak in the Attic near Los Gatos: Saratoga · San Jose · Cupertino .

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