Replacing the air handler did not end one Florida homeowner's long-running ceiling leak, and commenters think the underlying problem may still be inside the walls.

When leaks appear only while the AC is running, the problem can be more than an inconvenience. It can also be a sign of hidden damage that may suddenly become far more expensive the longer it goes unresolved.

What happened?

The leak in the Florida home appears only during AC use, the homeowner wrote in a post on Reddit. They said the recurring ceiling problem continued even after a recent air handler replacement, with the older drain piping and other wall-hidden components left in place.

Several commenters focused on the condensate system, saying a clogged or cracked drain line could explain the issue. 

They pointed to the way the water seems to move across the drywall before dripping down, while the soaked, sagging ceiling suggests the leak may have been spreading behind the surface for some time. One Redditor offered their advice: "At this point that drywall needs to come down. That could fall under a GC, a drywaller or a carpenter. I would schedule an HVAC company to come out after the drywall is down and see about testing and replacing the drains as much as possible."

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Why does it matter?

Water damage rarely stays a cosmetic issue for long — it can eventually lead to pricier consequences. Wet drywall can weaken, sag, and eventually fail, while moisture trapped inside ceilings or walls can create conditions for mold and lead to costly repairs, such as one homeowner who dealt with an unwanted surprise of a leak and thousands of dollars in repair estimates.

A partial HVAC job can leave older drain lines untouched.

That may lower the upfront bill, but if aging condensate piping is the real failure point, the leak — and the repair costs — may keep returning.

There is also an energy-cost factor. If an AC system is draining poorly, cycling incorrectly, or operating with hidden moisture issues, homeowners may end up paying for an inefficient setup while still dealing with interior damage. A cheap short-term fix is not always the least expensive outcome.

What can I do?

If a ceiling leak happens only when the AC is running, it is reasonable to start with an HVAC professional and specifically ask for the condensate system to be inspected, including the drain line, trap, pan, float switch, and any sections hidden inside the walls. A plumber or general contractor may still be needed to open and repair the ceiling, but identifying the source often starts with the cooling equipment.

Commenters said the sagging drywall should not be ignored, and they also warned against using bleach in the line because it can damage PVC glue. For routine maintenance, they recommended vinegar instead.

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Across the comments, the repeated warning was not to use bleach in the line, and to use white distilled vinegar instead.

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