An AC unit leaking water in a Leander or Cedar Park home is almost always a drainage problem, not a refrigerant problem. Carrier, whose factory authorized dealer network we belong to, names a clogged condensate drain line, a frozen evaporator coil and a damaged drain pan as the usual causes, and all three are fixable before they turn into a stained ceiling.
Where the water comes from
An air conditioner pulls moisture out of the air as it cools, and that moisture has to go somewhere. It drips off the indoor evaporator coil into a drain pan, then runs out of the house through the condensate line, which Carrier describes as a 3/4-inch PVC pipe running from the coil to a drain outside.
The 2021 International Residential Code requires that line to slope toward its outlet by at least 1/8 unit vertical for every 12 units horizontal. When anything interrupts that path, the water backs up and finds its own way out, usually onto a closet floor or through the ceiling under an attic unit.
Is it safe to keep running the AC while it leaks?
A leaking AC should be switched off at the thermostat until the cause is found. Carrier's guidance is that running a leaking unit could worsen the issue, because the system keeps producing water it cannot drain. Put towels or a pan under the drip, move anything valuable out of the way, and then start looking.
Speed matters for what is already wet. The EPA advises drying water-damaged areas and items within 24-48 hours to prevent mold growth. If the water has soaked drywall or ceiling material and you suspect mold in or around the air handler, the EPA also says not to run the HVAC system, since it could spread mold through the house.
A clogged condensate drain line
A clogged drain line is the most common reason an AC leaks. Carrier explains that dust on the coil mixes with the moisture the system removes and forms a sludge, and that algae and mold add to it over a cooling season. After a long Central Texas summer of near-constant running, a Leander drain line has had months to build that up.
Carrier lists the signs: standing water near the indoor unit, water marks on ceilings or floors, a musty smell from the unit or vents, weak cooling, or a system that shuts itself off. That last one is often the float switch doing its job, which is covered below.
A frozen evaporator coil
A frozen coil leaks when the ice melts, and it can leak even after the system is turned off. Carrier says ice usually forms from restricted airflow, most often a dirty filter, or from low refrigerant, and that melting ice can arrive faster than the drain can carry it away.
Check the filter first. Carrier recommends replacing it every one to three months. If a fresh filter does not stop the icing, the cause is refrigerant or airflow inside the equipment, and that is a job for a licensed technician rather than a homeowner.
A cracked or rusted drain pan
The primary drain pan sits under the indoor coil and collects every drop of condensate. Carrier notes that pans corrode or crack over time, with the risk rising as a system ages and in humid climates. A clear drain line with water still showing up under the unit often points to the pan itself.
What the backup drain and float switch are telling you
Water dripping from a pipe over a window or doorway is a warning, not a nuisance. The 2021 IRC requires a secondary drain or an auxiliary pan under any cooling coil where an overflow would damage the building, which describes most attic air handlers in Leander. That secondary drain has to discharge somewhere conspicuous enough to alert occupants that the primary drain has stopped.
The code sets the auxiliary pan at a minimum depth of 1.5 inches and at least 3 inches larger than the unit in width and length. Instead of a drain, some systems use a water-level switch conforming to UL 508 that shuts the equipment off before the pan overflows. If your AC quit and the pan under it holds water, the switch has probably saved your ceiling. It will keep the system off until the primary drain is cleared.
What you can safely check yourself
- The filter. A clogged filter is the cheapest cause to rule out and the easiest to fix.
- The outdoor end of the drain line. With the AC off, Carrier suggests a wet/dry vacuum at the outdoor exit to pull a clog out. If you are not sure which pipe is the condensate drain, leave it alone.
- The secondary pan. Standing water there means the primary drain is blocked, even if nothing has reached the ceiling yet.
Pouring vinegar down the line is common advice, but Carrier's own drain line guide notes that vinegar or bleach may not fully prevent clogs, because many clogs are debris rather than organic growth. Anything inside the cabinet, near the refrigerant lines or the wiring, is for a technician.
When to call
Call the same day if water is coming through a ceiling, soaking a floor, or the system has shut down in heat. Carrier treats a leak that is damaging ceilings, floors or drywall as an emergency, and so do we: that is what our emergency AC repair service is for. A slow drip, a musty smell or water in the secondary pan can usually be booked as a standard AC repair visit in the next day or two.
The fix that stops it happening again is maintenance. Carrier recommends having the drain line inspected and cleaned at least once a year, and the EPA advises keeping drip pans clean and drain lines flowing. We clear and flush the condensate line and check the pans on every maintenance visit.
Comfort Pros is a Carrier factory authorized dealer serving Leander, Cedar Park, Georgetown and Liberty Hill, licensed under TACL# TACLB116912E. Most leaks we see come down to a line that needed clearing. The goal is to catch it at the drip, not at the drywall.