Why Is My AC Leaking Water Inside My House?
Why Is My AC Leaking Water Inside My House? Water pooling around your indoor AC unit is almost always caused by a clogged condensate drain line, a cracked or overflowing drain pan, or a frozen evaporator coil that’s melting faster than the drainage system can handle. In South Carolina’s high-humidity climate, your AC removes significantly more moisture from the air than systems in drier regions — often producing 5–20 gallons of condensate per day during peak summer. That volume of water needs a clear path out of your home, and when anything blocks or breaks that path, the water ends up on your floors. Coastal Carolina Comfort diagnoses and repairs AC water leaks across Summerville, Charleston, Columbia, and the entire South Carolina Lowcountry and Midlands. Most condensate-related repairs are completed in a single same-day visit. Call (843) 708-8735. Why South Carolina Homes See More AC Water Leaks Understanding why this problem is so common in our region starts with understanding how much moisture your AC handles. A residential air conditioning system in South Carolina processes far more humidity than the same system would in Colorado, Arizona, or even the mid-Atlantic states. When warm, humid Lowcountry or Midlands air passes over the cold evaporator coil, moisture condenses on the coil’s surface — the same way water beads on a cold glass on a summer day. That condensation collects in a drain pan below the coil and flows through a drain line to the outside of your home. During a typical South Carolina summer day with 80%+ relative humidity, your system may remove 5–20 gallons of water from your indoor air. That’s a tremendous amount of water flowing through a ¾-inch PVC pipe every day for six months. The warm, wet environment inside that drain line is ideal for algae, mold, and bacterial growth — which is exactly what clogs it. This is why AC water leaks are one of the most common repair calls Coastal Carolina Comfort receives across the region, and why regular AC maintenance that includes drain line treatment is so important here. The 5 Most Common Causes of AC Water Leaks 1. Clogged Condensate Drain Line This is the cause in roughly 70% of AC water leak calls we respond to across South Carolina. The drain line — typically a ¾-inch PVC pipe running from the drain pan to an exterior exit point — becomes blocked by algae, mold, rust, or mineral deposits. Water backs up behind the clog, fills the drain pan, and overflows onto your floors. South Carolina’s humidity makes drain clogs far more common than in drier climates because the warm, constantly wet interior of the drain line is a perfect incubator for biological growth. In the Lowcountry, we see drain lines that clog within 3–6 months of cleaning if no preventive treatment is applied. The fix: A technician clears the clog using a wet/dry vacuum, nitrogen flush, or manual snake, then treats the line with an algaecide tablet or solution to inhibit regrowth. This is one of the most affordable AC repairs — typically $100–$200. The best prevention is flushing the drain line with vinegar monthly during cooling season and scheduling professional treatment during your annual maintenance visit. 2. Cracked or Rusted Drain Pan The drain pan sits beneath the evaporator coil and catches condensation before it reaches the drain line. Over time — especially in the high-moisture environment inside a South Carolina air handler — metal drain pans rust through and plastic pans can crack. When the pan is compromised, water bypasses the drain line entirely and drips directly onto the floor, into the ceiling, or into the crawl space below. The fix: Drain pan replacement. Secondary drain pans (the backup pan beneath the air handler) are accessible and relatively inexpensive to replace. Primary drain pans (integrated into the coil assembly) are more involved and may require partial disassembly of the air handler. Costs typically range from $200–$600 depending on accessibility and pan type. 3. Frozen Evaporator Coil Melting When the evaporator coil freezes — due to low refrigerant, restricted airflow, or a blower motor failure — the ice buildup can be substantial. When the system shuts off or the ice begins to melt, the volume of water released can overwhelm the drain pan and flood the area around the unit. This is different from a normal condensate leak because the water volume is much larger and more sudden. If you see ice on the indoor unit or the copper refrigerant lines, you’re dealing with a coil freeze — not a simple drain clog. Read our complete guide on frozen evaporator coils in humid South Carolina weather. The fix: Turn the system off to allow the coil to thaw completely (2–3 hours minimum). Place towels or a shallow pan to catch the meltwater. Then call for professional diagnosis to identify why the coil froze in the first place — the freeze is a symptom, not the root cause. 4. Disconnected or Damaged Drain Line The PVC drain line can become disconnected from the drain pan fitting, cracked from physical impact, or separated at a joint due to poor installation or settling of the home. When this happens, condensate exits the system but misses the drain path — flowing instead into ceilings, walls, or onto floors at the point of disconnection. This is more common in homes where the air handler is located in the attic — found frequently across Charleston, Summerville, and Columbia — because the drain line has a longer run and more joints that can separate over time. The fix: Reattach, reseal, or replace the damaged drain line section. This is typically a straightforward repair costing $100–$300 depending on accessibility and the extent of the damage. 5. Condensate Pump Failure Some AC installations — particularly where the air handler is in a basement, crawl space, or interior closet below the level of the exterior drain exit — use a condensate pump to move water uphill to an exit point. When
AC Unit Making Strange Noises: What Each Sound Means and When to Call for Repair
AC Unit Making Strange Noises: What Each Sound Means and When to Call for Repair A healthy air conditioning system produces a consistent, low-level hum during operation. When you hear new sounds — grinding, buzzing, clicking, banging, hissing, or screeching — each noise points to a specific mechanical or electrical problem. Identifying what the sound is and where it’s coming from helps determine whether you need immediate service, can schedule a repair within a few days, or simply have a minor issue that’s easy to resolve. Coastal Carolina Comfort’s NATE-certified technicians diagnose and repair noisy AC systems across Summerville, Charleston, Columbia, and the entire South Carolina Lowcountry and Midlands. We identify the source of the sound, explain what’s causing it, and provide upfront pricing before any work begins. Call (843) 708-8735. A Sound-by-Sound Diagnostic Guide Grinding: Failing Motor Bearings What it sounds like: A metallic grinding, scraping, or growling that gets louder over time. It may be intermittent at first and become constant. Where it comes from: Usually the indoor blower motor or the outdoor condenser fan motor. What’s happening: The motor bearings that allow the shaft to spin freely are wearing out. As the bearings degrade, metal contacts metal, creating the grinding sound. Eventually the motor seizes completely — which turns a $350–$700 motor replacement into a potential compressor failure if the system overheats. Urgency level: Schedule within 1–3 days. A grinding motor can fail at any time. Continuing to run the system accelerates the damage but won’t cause an immediate safety hazard. The longer you wait, the higher the chance the motor seizes during a peak-heat day when you need it most. South Carolina note: The extended cooling season in the Lowcountry and Midlands puts more annual hours on motor bearings than most of the country. A motor that might last 15 years in a cooler climate may wear out in 10–12 years here because it runs 6+ months per year. Buzzing: Electrical Problems What it sounds like: A steady electrical buzz or hum, louder than the system’s normal operating sound. May come from the outdoor unit, indoor unit, or both. What’s happening: Buzzing from the outdoor unit most commonly indicates a failing contactor (the electrical relay that starts the compressor) or loose wiring connections vibrating during operation. Buzzing from the indoor unit may point to a failing transformer, a relay issue, or a blower motor with electrical problems. Urgency level: Schedule within 1–2 days. Electrical issues can worsen without warning. A contactor that’s arcing or buzzing can weld itself shut (causing the system to run nonstop), fail open (causing a complete shutdown), or create a fire risk if left unaddressed. If the buzzing is accompanied by a burning smell, turn the system off at the breaker and call for emergency AC repair in the Lowcountry. Clicking: Capacitor or Control Board Issues What it sounds like: Repeated clicking sounds at startup — the system tries to start, clicks, pauses, tries again, clicks. Or a single click followed by silence instead of the compressor engaging. What’s happening: This is typically a failed run capacitor trying and failing to deliver the electrical boost the compressor needs to start. The click is the contactor engaging, but without sufficient capacitance, the compressor can’t turn over. The system tries repeatedly, clicking each time. Less commonly, clicking indicates a control board relay failure — the electronic brain of the system is sending the start signal but a relay on the board isn’t completing the circuit. Urgency level: Same-day to next-day. The system won’t cool in this state. If the weather is mild, next-day service is fine. In South Carolina summer heat, this is a same-day call. A failed capacitor is one of the quickest and most affordable repairs — typically $150–$300 including parts and labor. Banging or Clanking: Loose or Broken Internal Components What it sounds like: A rhythmic banging, clanking, or knocking — usually from the outdoor unit. The sound follows the fan’s rotation cycle. What’s happening: Something inside the unit is loose and making contact with a moving part. The most common causes are a broken fan blade striking the housing, a loose compressor mounting bolt allowing the compressor to vibrate excessively, or debris (a stick, acorn, or small animal) caught inside the condenser housing. Urgency level: Turn off and schedule same-day. A broken fan blade or loose component can cause escalating damage to other parts with every rotation. Turn the system off at the thermostat and call for service. Do not reach inside the unit to investigate. Hissing or Bubbling: Refrigerant Leak What it sounds like: A persistent hiss from the indoor or outdoor unit, or a bubbling/gurgling sound from the refrigerant lines. What’s happening: Refrigerant is escaping through a hole or crack in the copper lines, coil, or fittings. A hiss indicates gas-phase refrigerant escaping under pressure. A bubbling sound indicates the leak is in a section where refrigerant is in liquid phase. Urgency level: Schedule within 1–2 days. A refrigerant leak won’t cause immediate damage to your home, but every day it leaks reduces cooling capacity and forces the compressor to work harder. Running a system with critically low refrigerant can cause compressor damage. If you also notice ice forming on the indoor unit, turn the system off. In South Carolina’s coastal and humid environment, refrigerant line corrosion is more common than in drier climates — particularly on homes near the coast where salt air accelerates copper degradation. Our guide on what South Carolina humidity does to your cooling system explains why. Screeching or Squealing: Belt or Motor Issues What it sounds like: A high-pitched screech or squeal, usually at startup, that may fade as the system reaches operating speed. What’s happening: In older systems with belt-driven blower motors, a worn or misaligned belt slips and squeals — similar to a car’s serpentine belt. In newer direct-drive systems, the screech may indicate a failing motor bearing or a blower wheel rubbing against its housing. Urgency level: Schedule within