By Commercial Service Company · November 3, 2026
A commercial AC water leak rarely starts with a flood. It starts with a small brown ring on a ceiling tile, a drip near a register, or a rooftop unit that just stopped cooling for no obvious reason. In almost every case, the cause is the same: the condensate drain line has clogged and the water that's supposed to leave the building is backing up instead.
For restaurant, grocery, and office building owners in Little Rock, Conway, Benton, Bryant, Maumelle, Jacksonville, Searcy, Russellville and the rest of central Arkansas, this is one of the most common commercial AC service calls we run — and one of the easiest to prevent with regular attention.
Why Condensate Lines Clog in the First Place
Every air conditioning system pulls moisture out of the air as it cools. That water collects in a drain pan and flows out through a condensate line, usually PVC pipe, to a drain or to the outside of the building. The problem is what travels with that water:
- Algae and biofilm that grow inside a dark, consistently wet pipe
- Dust, dirt, and insulation fibers pulled through the air handler over time
- Rust and scale flaking off older metal drain pans
- Insect and rodent debris in line sections that run through walls or attics
Over months, this buildup narrows the inside of the drain line until water can't move through fast enough. Eventually it backs up into the drain pan, overflows, and starts finding the path of least resistance — usually down through a ceiling.
The Ceiling Stains and Shutdowns That Follow
Once a drain line is clogged, a few things typically happen, sometimes all at once:
- Water stains spread across ceiling tiles or drywall below the unit, often in a back room, hallway, or above a walk-in cooler area
- Standing water sits in the drain pan, which can lead to odors and, over time, damage to the pan itself
- The unit shuts itself off unexpectedly, even though nothing seems wrong with the cooling system electrically
That last point surprises a lot of owners. The unit isn't broken — it's doing exactly what it was designed to do.
Why the Unit Shuts Off: Float Switches
Most commercial AC equipment includes a condensate safety switch, often called a float switch, mounted in or near the drain pan. When water rises above a set level — a sign the drain line is clogged or blocked — that switch cuts power to the system. This is a protective feature, not a malfunction. It's there specifically to stop a slow drain clog from turning into a ceiling collapse, soaked insulation, or damaged electrical components above a dining room or sales floor.
If your system keeps shutting off and a technician finds the float switch triggering, don't have anyone bypass or remove it. That switch is doing its job. The real fix is clearing whatever is blocking the drain, not disabling the warning.
Maintenance That Keeps Drains Clear
Condensate drain problems are largely preventable with routine attention. As general best practice, a maintenance visit should include:
- Checking the drain pan for standing water, rust, or cracks
- Flushing or clearing the condensate line to remove buildup before it restricts flow
- Verifying the float switch is seated correctly and shuts the unit off when it should
- Confirming the line has proper slope so water keeps moving instead of sitting
- Checking insulation on the line in humid or unconditioned spaces, since a sweating line can mimic a leak
For kitchens, grocery coolers, and any space running AC heavily through an Arkansas summer, we recommend having drains checked at each seasonal service visit rather than waiting for a stain to show up on the ceiling. By the time you see water, the clog has usually been building for a while.
Don't Guess at the Cause
Water near an AC unit can come from more than one source — a clogged drain, a cracked pan, insulation failure, or in some cases a refrigerant issue affecting the coil. Diagnosing which one you're dealing with, and safely clearing a line or servicing the unit, should be left to a licensed technician. Reaching into an air handler or messing with electrical components on a rooftop unit isn't something building staff should take on themselves.
If you're dealing with a ceiling stain, a dripping vent, or a commercial AC unit that keeps shutting off, don't wait for it to get worse. Call Commercial Service Company at 501-548-2374 and we'll get a technician out to find the cause and get your system draining the way it should.