How to fix an air conditioner leak
We'll help you locate the leak and clear the condensate drain—or know when to call an HVAC technician.
What you'll need
- Wet/dry vacuum (for clearing drain)
- Bleach or vinegar (for drain flush)
- Replacement drain pan (if cracked)
At a glance
- Shut off the AC before working on it.
- Check the condensate drain line and drain pan for clogs or cracks.
- Clear a clogged drain with a vacuum or bleach flush; replace a cracked pan.
- Refrigerant leaks require an HVAC technician—do not attempt to repair.
Quick triage — pick your path
Get started
Choose the option that matches what you see. You can jump straight to that section.
- Follow this guide Work through location and repair steps.
- Clear the condensate drain Water is backing up from the drain; the drain is likely clogged.
- Check the drain pan Water is overflowing from the pan or dripping from the unit.
- When to call an HVAC technician Refrigerant leak, frozen coil, or drain is inaccessible.
Steps
Goal: Locate the leak and clear the condensate drain—or call an HVAC technician.
- Shut off the AC. See Shut off AC.
- Locate the condensate drain and pan. See Locate drain.
- Clear the drain or fix the pan. See Clear drain and Drain pan.
- Call an HVAC technician for refrigerant or coil issues. See When to get help.
Shut off AC
Goal: Work safely with the unit off.
- Turn off the thermostat and circuit breaker. Confirm the unit is off.
- Good: No fan or compressor operation. Proceed to Locate drain.
- Bad: Unsure which breaker—turn off the main AC breaker.
Locate drain
Goal: Find the condensate drain path.
- Trace the condensate drain from the indoor unit to the exit. Find the drain pan under the evaporator coil.
- Good: You identify the drain path and pan. Proceed to Clear drain.
- Bad: Cannot access—call an HVAC technician.
Clear drain
Goal: Clear a clogged condensate drain.
- Use a wet/dry vacuum on the drain outlet to pull the clog. Or pour bleach or vinegar into the drain access and flush with water.
- Good: Drain flows freely. Proceed to Verification.
- Bad: Drain is still clogged—try a drain snake or call an HVAC technician.
Drain pan
Goal: Fix or replace a cracked or overflowing drain pan.
- Inspect the drain pan for cracks. Replace if cracked. If overflowing, clear the drain. Confirm the drain slopes downhill.
- Good: Pan is intact and drain is clear. Proceed to Verification.
- Bad: Pan is cracked and not accessible—call an HVAC technician.
When to get help
Call an HVAC technician if:
- The leak is refrigerant (oily residue, hissing sound).
- The evaporator coil is frozen.
- The drain is inside the wall and inaccessible.
- You are not comfortable with the repair.
Do not attempt to repair refrigerant leaks. The technician must be EPA-certified.
Verification
- Condensate drain flows freely when the AC runs.
- No water pooling in the drain pan.
- No drips from the unit.
- AC operates normally without leaking.
Reviewed by Blackbox Atlas
Frequently asked questions
- Where do air conditioners usually leak?
- Common spots: the condensate drain line (clogged with algae or mold), the drain pan (cracked or overflowing), and the drain line connection. Refrigerant leaks are less common but require a professional. Ice melting can also cause overflow.
- Can I fix an AC leak myself?
- Yes, for condensate drain clogs and some drain pan issues. Clear the drain with a vacuum or bleach flush. Replace a cracked drain pan if you can access it. Refrigerant leaks require an HVAC technician.
- When should I call a plumber for an AC leak?
- Call an HVAC technician for refrigerant leaks, a frozen evaporator coil, or if the drain is inside the wall and inaccessible. For a clogged condensate drain that you can reach, DIY is usually fine.
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