Why Does My AC Unit Sound Like Running Water and How Do I Make It Stop?

The sound of running water might be relaxing in most situations, but that’s not the case when it’s coming from your AC unit. Fortunately, many of the issues that cause an AC unit to sound like a forest creek are easily fixable for beginning DIYers or are a quick fix for a pro. If your AC sounds like water running, here’s what might be going on. 

1. The Drain Pan Is Full

Along with cooling air, AC units also strip excess moisture from it, a process known as dehumidifying. This means that AC units need to drain excess water somewhere. If your unit is making a running water sound, it could indicate that your drainage pan is full and overflowing.

A full drain pan could be caused by a clogged drain pipe, frozen coils, or improper installation. Regardless of the reason, an overflowing drain pan can cause flood damage in your home if you don’t take a look at it pronto. You can clear an AC drain line clog yourself or call a pro to do it.

2. The Air Filter Is Dirty

Although they may seem unrelated, a dirty air filter can contribute to the running water sound your AC is making. By blocking up the unit, a dirty filter can cause your evaporator coil to freeze. Eventually, the frozen coils may begin to thaw and leak around your AC unit, causing a running water sound.

You should change your air filter every one to three months. Making sure your filter is clean will help you avoid an AC water running sound caused by frozen and melting coils and ensure you’re breathing clean air.

3. The Refrigerant Level Is Low

A low level of refrigerant in your AC unit can make it impossible for your evaporator coil to absorb heat from the air as it’s designed to do. As with a dirty filter, this issue can cause the coils to freeze and accumulate condensation. Replacing refrigerant is a complex and dangerous process, so reach out to a local AC repair pro to solve this problem.

4. The Evaporator Coil Is Dirty (or Frozen)

We’ve mentioned the evaporator coil a few times now, so it’s time to add it to the list as a primary cause rather than a secondary one. As suggested, a dirty or frozen evaporator coil can cause a lot of problems in your AC unit. Clean your air conditioner coils regularly to prevent a running water sound caused by freezing. 

5. The Thermostat Is Broken

If your AC’s thermostat is broken, you guessed it: The unit might cool down too far and freeze up, causing condensation to accumulate, run, and potentially flood your home. Telltale signs that the thermostat is broken include erratic AC unit behavior and temperatures that don’t line up with your settings. You may be able to replace the thermostat without replacing the entire unit.

6. The Blower Is Broken

The blower inside your AC unit moves air across the evaporator coil, where it undergoes the heat transfer process. If the blower isn’t working properly, the coil may freeze and eventually thaw and melt. A professional can easily replace a broken AC blower, but this isn’t a DIY fix.

Other Water Sounds Your AC Unit Could Make

As if running water weren’t enough, there are a few other common watery sounds your AC unit could be making, but not all of them immediately spell trouble. 

Dripping

Good news: In general, a dripping sound coming from your AC unit is nothing to worry about. This is a normal part of the dehumidifying process and is caused by the condensed water falling into the drip pan, which is exactly what it’s supposed to do.

However, if the sound becomes annoying to you, you might consider emptying the drip pan. and If it’s really bothersome, it may indicate a blocked condensation drain pipe, which can cause similar flooding problems as those described above.

Gurgling or Bubbling

Gurgling or bubbling sounds coming from your AC unit may indicate an issue with the refrigerant system. The refrigerant might be leaking, which can cause your AC unit to have low pressure and not work properly, or there may be an air bubble in the refrigerant line.

According to the U.S. Environmental Protection Agency, refrigerant exposure is associated with “toxicity, flammability, asphyxiation, and physical hazards.” So, if you hear any suspicious HVAC noises and have a strong inclination that refrigerant could be to blame, don’t wait to reach out to a pro, and don’t try to DIY a fix. 

Hissing

Hissing sounds can also point to issues with the refrigerant system, including refrigerant leaks. However, hissing can also indicate internal valve leaks or a malfunctioning compressor. Again, an AC pro is the best person to diagnose and fix these issues. Luckily, you’ll likely be able to replace just the faulty parts instead of the whole unit.