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AC Leaking Water Inside
in Tempe, AZ
Your AC removes humidity from the air and that water has to go somewhere. It runs through a drain line and out of the house. In Tempe, monsoon season from July through September pushes indoor humidity high enough that the drain system gets overwhelmed, especially in older homes in central Tempe where drain lines have not been serviced in years. Left alone, water backs up and ruins ceilings, walls, and flooring.
Quick Answer
Water leaking from your indoor AC unit in Tempe usually means the drain line is clogged with algae or the drain pan has cracked. In the monsoon season, humidity spikes and the coil pulls more moisture out of the air than the drain can handle. A technician clears the line and checks the pan. Call (928) 564-6468 if you see water near the unit — it can damage drywall and cause mold within 24 hours.
Telltale Signs
Warning Signs to Watch For
- Water stains on the ceiling below the air handler
- Standing water in the secondary drain pan under the unit
- A musty smell near the indoor unit or in the vents
- Water dripping from the unit itself or from the ceiling near it
- The system shuts off on its own and won't restart
Root Causes
What Causes AC Leaking Water Inside?
Clogged Condensate Drain Line
The drain line carries water from the indoor coil to the outside or to a floor drain. Algae and mold grow inside the line in Tempe's summer humidity and eventually form a plug. When the line is blocked, water backs up into the drain pan and overflows onto the ceiling or floor.
The Fix
Drain Line Flush and Clear
A technician uses a wet-vac or pressurized flush to clear the blockage and then treats the line with a drain tablet to slow algae growth. Flushing the line once a year before monsoon season keeps this from repeating.
Cracked or Rusted Drain Pan
The drain pan sits under the coil and catches any water before it reaches the floor. Units installed before 2000 in Tempe often have metal pans that rust through, or older plastic pans that crack from years of heat cycling in attic installations. A cracked pan leaks no matter how clear the drain line is.
The Fix
Drain Pan Replacement
A technician removes the old pan and installs a new one sized for your unit. On attic-mounted systems common in Tempe homes from the 1990s, they also check that the secondary pan below the unit is intact.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Clogged Condensate Drain Line | Cracked or Rusted Drain Pan |
|---|---|---|
| Water backing up at the drain line clean-out port | ||
| Drain line is clear but water still puddles under unit | ||
| Musty smell from vents during monsoon season | ||
| Visible rust or crack on the metal pan under the coil | ||
| System shuts off due to a float switch trigger |
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