It’s a hot day, you flip on your air conditioning, and within a few minutes, you feel that cool relief—until you notice something wet near your feet. If you’ve spotted water dripping inside your car while the AC is running, you're not alone. It's a common issue, but it's also one that can quickly go from a minor inconvenience to real damage if ignored.
While a little condensation under the car is perfectly normal, water leaking into the cabin is not. Here’s what might be causing it and what you should do about it.
How Your AC Normally Handles Water
When your car’s air conditioning is running, it’s not just cooling the air—it’s also removing moisture. That moisture collects on the evaporator coil, condenses into water, and then drains out of the car through a small rubber hose called the AC drain line.
Under normal conditions, all that water exits beneath your vehicle without you even noticing. So, when you see it inside the cabin instead, it usually means something isn’t draining properly.
Clogged Drain Line
Over time, the AC drain line can become clogged with dirt, leaves, mold, or debris, especially if your car is parked outside often. When the line is blocked, the condensation has nowhere to go and starts backing up into the HVAC system.
Eventually, that water finds its way out—usually onto the passenger-side floor. You might not notice it at first, but over time, wet carpet can lead to mold, mildew, and musty smells, not to mention electrical issues if moisture gets into nearby components.
A quick way to check is to look under your car when the AC has been running. If there’s no water dripping from the usual spot near the passenger side, there’s a good chance your drain line is blocked.
Damaged or Disconnected Drain Hose
In some cases, the hose itself may be damaged, disconnected, or improperly sealed, especially if recent repairs or modifications were made around the HVAC system. This can cause water to leak directly into the interior rather than draining out as it should.
It’s a simple problem, but it often requires accessing parts of the dashboard or under the car, so it’s best handled by a professional.
Frozen or Dirty Evaporator Coil
If the evaporator coil becomes dirty or frozen, condensation may build up too quickly for the drain system to handle, leading to water overflow. A frozen coil can also block the airflow and trap excess moisture inside the unit.
In this case, you might also notice your AC isn’t blowing as cold as it used to—or that airflow seems weaker than normal. That’s a sign it’s time for an inspection.
How to Prevent Future Leaks
Keeping your AC system clean and well-maintained goes a long way in preventing water leaks. Replacing the cabin air filter regularly helps reduce debris buildup, and running the fan without AC for a few minutes before turning off the car can help dry out any lingering moisture.
If you’ve had a clogged drain line before, ask the technicians to check it during routine maintenance—it’s a quick service that can prevent repeat issues.
Don't let water leaks damage your interior—trust Davenport Motor Company in Plano, TX, to keep your AC working like it should. Book your appointment today!