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Air Conditioner Condensate drain line and pan: What It Does and Signs It's Failing

The tray under the indoor coil that catches water dripping off it, and the hose or pipe that carries the water outside or to a drain. Portable and window units hold water in a tank or base pan with a drain cap.

How it works

Condensate runs by gravity from the pan through the line. Ducted and ceiling units may add a pump and a float switch.

Signs it is failing

• Water dripping from the indoor unit
• Water stains on the wall below the unit
• A full-tank or drain code
• Musty smell
• Gurgling from the drain line

Drain and full-tank codes point here. On portables, LG and Midea have you drain the tank through the cap at the back into a shallow pan, or hook up a drain hose for humid weather.

Can you replace it yourself?

With the unit off, check that the outside end of the drain hose isn't blocked or under water. DOE suggests clearing drain channels with a stiff wire. On portable units, empty the tank and refit the cap firmly.

Buying the right part

Drain hose is generic. Use the size the original fits and keep a downhill slope.

Error codes linked to the condensate drain line and pan

• A3Condensate water level too highDaikin
• 53Drain pump errorFujitsu
• E9Condensate overflow protectionGree
• CH04Drain problem or water tank fullLG
• P1Portable AC water tank is fullMidea
• P4 / P5Drain sensor or drain pump problemMitsubishi Electric
• PAShut down to prevent a water leakMitsubishi Electric
• E153 / E665Drain pump or float switch problemSamsung

Last reviewed 2026-10-19.