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Air Conditioner Condensate pump and float switch: What It Does and Signs It's Failing

Ceiling cassettes and ducted units that can't drain by gravity use a small pump to lift water out. A float switch in the pan stops the system before the pan overflows.

How it works

As water rises, the float lifts and the pump runs. If the level stays high, the switch shuts the system down and a drain code appears.

Signs it is failing

• Unit shuts off with a drain or float switch code
• Water leaking from a ceiling cassette
• Pump humming but no water leaving
• Slime buildup in the pan

Daikin and Fujitsu tie drain-level codes to a blocked line, a failing pump or the float switch. Fujitsu triggers its code if the float stays up for 3 minutes.

Can you replace it yourself?

Turn off power, clean the pan and check the drain line for blockage. Never disable the float switch; it's what stops water from coming through your ceiling. The pump is built into the indoor unit and wired to its board, often overhead, so replacement is a tech job.

Buying the right part

Match the pump's lift and voltage to the unit. OEM pumps fit the original mounts.

Error codes linked to the condensate pump and float switch

• A3Condensate water level too highDaikin
• 53Drain pump errorFujitsu
• E6Indoor and outdoor units can't communicateGree
• 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.