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What to do if…
an air-conditioning or HVAC unit starts leaking water indoors

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy USA guide

Short answer

Turn the system off using the thermostat or its normal controls if you can do so without approaching water or wet electrical equipment. Keep people away from the leak, contain accessible water safely, and arrange an HVAC assessment before using the system again.

Do not do these things

  • Do not keep restarting the system to see whether the leak returns.
  • Do not touch wet outlets, switches, wiring, appliances, electrical panels, or internal HVAC components.
  • Do not stand in water to reach a thermostat, plug, disconnect switch, or circuit breaker.
  • Do not remove access panels or reach inside the HVAC unit.
  • Do not pour drain cleaner, bleach, or another chemical into an unfamiliar condensate line.
  • Do not press, puncture, or stand beneath a sagging or bulging ceiling.
  • Do not use a fan, dehumidifier, extension cord, or wet vacuum where its plug, cord, or motor could contact water.

What to do now

  1. Set a central system’s thermostat to off, or switch a room or portable unit off using its normal controls, if there is a dry and safe path. Leave the system off while the leak is being assessed.
  2. Keep children and pets away from the wet area. Move away from any sagging ceiling or water that is spreading toward electrical equipment.
  3. If water is coming through or near a light fixture, outlet, electrical panel, wiring, or powered appliance, do not touch it or operate nearby switches. Call 911 for sparks, smoke, fire, a burning smell, or another immediate electrical danger.
  4. Place a bucket or waterproof container beneath an accessible drip when it is safe. Use towels to limit water spreading across dry flooring, but do not work beneath a bulging ceiling or near an electrical hazard.
  5. Move dry furniture, electronics, rugs, and other belongings away from the leak without crossing standing water.
  6. From a safe distance, note where the water appears to be coming from, such as beneath the unit, an overflow pan, a visible pipe, or a ceiling vent. Take photographs of the leak, nearby damage, and thermostat setting without opening the equipment.
  7. Contact a qualified HVAC contractor. If electrical equipment, outlets, wiring, or a panel became wet, also arrange an assessment by a qualified electrician before using the affected equipment.
  8. If you rent, notify the landlord, property manager, or emergency maintenance service promptly. State that the HVAC system is off, describe where the water is appearing, and keep a copy of the message.
  9. Dry safely accessible surfaces promptly with towels. Use a fan or dehumidifier only after electrical hazards have been ruled out and only from a dry, undamaged outlet.
  10. If turning off the system makes the home dangerously hot, move to a cooler place. Call 911 if anyone develops confusion, loss of consciousness, seizures, or other signs of severe heat illness.

What can wait

You do not need to diagnose the fault, open the unit, clear a condensate line, select replacement equipment, decide who is financially responsible, or begin an insurance claim immediately. First stop the system, avoid electrical hazards, limit the spread of water, document what happened, and arrange an assessment.

Important reassurance

A water leak does not by itself mean the entire HVAC system must be replaced. Several drainage, condensation, and equipment problems can cause indoor leaking, and stopping the system promptly can help limit further damage while the cause is identified.

Scope note

This guide covers the first safe actions after discovering an indoor water leak from an air-conditioning or HVAC unit. Repairs, electrical inspection, water-damage restoration, mold cleanup, insurance questions, and responsibility for costs may require qualified specialists.

Important note

This is general information, not technical, electrical, medical, insurance, legal, or other professional advice. Follow emergency-service instructions and advice from qualified professionals who can inspect the property directly.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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