Why Is My Air Conditioner Making Loud Noises? A Portland Tech Explains

Concerned about the noises coming from your AC? The noises are usually a symptom of a deeper problem with your AC.

No worries, we’re here to help!

The first step is diagnosing the issue by listening closely to the noises. What sounds are being made? Three of the most common noises your AC can make include:

  • Gurgling
  • Clicking
  • Slamming

In this blog, we’ll breakdown the potential causes of these noises and what you can do to fix the root problems.


Rather have your AC fixed ASAP? Contact Four Seasons. You can schedule fast, same-day AC repairs with us. Schedule today!


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Noise #1: Gurgling

If you hear gurgling noises coming from your AC, it’s most likely because of:

1. A refrigerant leak:

Gurgling noises are a good sign that you have a refrigerant leak.

What exactly is refrigerant? It’s a cold chemical agent that absorbs heat from your home’s air and dumps the heat outside your home. When there is a refrigerant leak, the gurgling noise comes from air entering the leak site.

If you do have a refrigerant leak, your AC won’t be able to cool your home as effectively or efficiently. So, if you think a refrigerant leak is your issue, you’ll want to contact an HVAC professional to seal the leak and refill your refrigerant since the refrigerant is a toxic substance.

2. A clogged condensate drain line:

Your indoor AC unit houses the evaporator coil, where the cold refrigerant lives. When your home's warm air contacts the cold refrigerant via the coil, condensate forms. The condensate gathers around the base of your evaporator coil and is moved outside via the condensate drain line.

Over time, dirt, debris, and mold clogs your drain line. The clog causes the condensate to back up the line and gurgling sounds are produced in the process.

End of the condensate drain line

To unclog your drain line, you'll need a wet/dry vacuum. Once you acquire one, follow the below instructions:

  1. Find the end of your condensate drain line — it’ll look like a white PVC pipe attached to your exterior wall.
  2. Attach the vacuum hose to the end of the drain line.
  3. Run the vacuum for 2 minutes.
  4. Check the vacuum to see if you removed the clog. If you see a lot of brown-colored water and debris, you’ve probably removed the clog.

If post-vacuum, you don’t see brown colored water or you still hear a gurgling noise, the clog is probably higher up in your drain line. You'll need to contact an HVAC professional to prevent damaging your AC system.

Noise #2: Clicking

Your AC clicks but doesn’t turn on. What’s going on? You most likely have one of the following issues:

1. Your thermostat is broken: If you're near your thermostat and hear constant clicking, the thermostat has a broken relay. The relay part opens and closes to turn on/off your AC.

2. Your capacitor is broken: If you have an older AC, you have a capacitor in your outdoor AC unit. The capacitor acts like a big battery and gives the AC the extra boost it needs to start up.

If you hear clicking around your outdoor unit, your capacitor most likely has failed. And now your outdoor unit is trying to startup without the capacitor's help.

If you think your thermostat or capacitor is broken, you’ll need to contact an HVAC expert.

Noise #3: Slamming

Slamming noises can come from either your indoor or outdoor unit.

  • If the slamming noise is coming from your indoor unit, it’s probably your blower fan. The fan pulls in warm air from your home for your AC to cool then redistributes the air throughout your home. Over time, the fan mounts can loosen. Once they’re loose, the fan will crash into its casing. To fix a loose blower fan, contact an HVAC professional to tighten the fan’s mounts.

If the slamming noise is coming from your outdoor unit, you probably have an issue with your compressor springs. The compressor springs in the outdoor unit uphold the refrigerant pumps. When the springs wear out, the pumps slam against the compressor's casing. Compressor springs are difficult and expensive to repair. An HVAC technician can advise you if a repair is possible or if you'll have to replace the entire compressor.

Want your AC to be quiet again? Contact Four Seasons

For over 40 years, we have been providing reliable AC repairs to Portland homeowners. Our technicians can repair all brands and models.

Beyond just reliable service, we also provide convenience to our customers. You can book same-day service appointments.

Schedule service today!schedu