As your air conditioner cools air, it also removes humidity — pulling moisture out of the air and collecting it as liquid water on the evaporator coil. This condensate drains through a line to the outside. In Phoenix, this process is especially active during monsoon season (July–September), when outdoor humidity can jump from under 10% to 60%+ after a thunderstorm. The condensate system that handled dry Phoenix air all spring may not keep up with monsoon humidity loads.
Locate the PVC drain line exiting your air handler (usually a white 3/4″ pipe). Find the access cap or T-fitting. Pour 1/2 cup of distilled white vinegar into the line — this kills algae and breaks up buildup. Wait 30 minutes, then flush with clean water. If the drain is severely blocked, use a wet-dry vac at the exterior drain end to suck out the clog. Repeat the vinegar treatment monthly during monsoon season.
If water is already dripping through your ceiling or into your attic insulation, turn the AC off immediately to stop additional water production. Remove standing water from the drain pan to prevent secondary overflow. Then call a technician — attic insulation soaked with AC condensate can grow mold within 24–48 hours in Phoenix heat. See our Phoenix AC repair service or call 480 478-2616 right away.
Frequently Asked Questions
Answered by Discount AC & Refrigeration — EPA Certified · ROC #361623 · Phoenix, AZ
Why is water leaking from my AC unit inside my house?
The most common causes are a clogged condensate drain line, a cracked or overflowing drain pan, dirty evaporator coils causing excess condensation, or a frozen coil that melts and overwhelms the drain. In Phoenix, monsoon season dramatically increases humidity, which means your AC removes more moisture from the air and the condensate drain handles more volume than usual.
What is the condensate drain line and why does it clog?
The condensate drain line carries the water your AC removes from indoor air outside the home. Over time, algae, mold, and debris build up inside the line, especially in humid monsoon months. A full clog causes the drain pan to overflow, and water leaks inside the home. Clearing the line with a wet/dry vacuum or compressed air typically resolves the issue.
How do I unclog my AC condensate drain line myself?
Turn the AC off. Find the condensate drain access port (a white PVC cap near the indoor unit). Pour a cup of diluted bleach (1:16 bleach-to-water ratio) into the port and wait 30 minutes. Then use a wet/dry vac attached to the outdoor drain pipe end to suck out the clog. If this doesn’t work, the clog may be further down or the line may be broken — call a technician.
Can a leaking AC cause water damage to my home?
Yes, quickly. The drain pan holds only a small volume of water. Once it overflows, water can soak into drywall, ceilings, and subflooring within hours, especially in a Phoenix home during monsoon season when the AC is working hardest. If you see water pooling around your indoor unit, turn the system off immediately and address the drain clog before turning it back on.
Is the water leaking from my AC dangerous?
The water itself is not toxic, but standing water around electrical components creates a shock hazard. Additionally, moisture in drywall and insulation creates conditions for mold growth within 24–48 hours in Phoenix’s summer heat. Turn off the system, clean up the water, and fix the drain issue promptly.
Why is my AC leaking more water during monsoon season in Phoenix?
During monsoon season, Phoenix’s humidity rises significantly (sometimes reaching 50–60%+). Your AC works harder to remove that moisture from the air, producing far more condensate than in dry summer months. A drain line that handles the load in June may get overwhelmed in August. This is why flushing the condensate drain before monsoon season is a key part of annual AC prep.
What is the condensate drain float switch and how does it work?
The float switch is a safety device installed in the drain pan. When water in the pan rises above a set level (indicating a clogged drain), the float switch cuts power to the AC to prevent overflow. If your AC simply won’t turn on and you notice water in the drain pan, the float switch is likely the reason — clear the drain clog and the system will restart.
Can I just empty the drain pan instead of clearing the clog?
Emptying the pan will temporarily stop the leaking, but the clog remains and the pan will fill and overflow again within hours. You need to clear the blockage in the drain line itself. Think of it like bailing water from a sinking boat without plugging the hole.
What if I clear the drain and my AC is still leaking water?
If the drain line is clear and water is still leaking, other causes include: a cracked or warped drain pan that needs replacement, frozen evaporator coils caused by a dirty filter or low refrigerant, or improper installation where the line doesn’t drain at a proper slope. A technician can diagnose and resolve any of these in a single visit.
How quickly can Discount AC & Refrigeration come for a water leak from my AC?
We treat indoor AC water leaks as urgent, especially during monsoon season when they can cause rapid water damage. We serve the Phoenix metro 6 AM–midnight, 7 days a week. Call (480) 478-2616 for same-day or next-day service.
