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ServiceMax Blog

What a Hissing AC Means


The summer season is underway, and there’s nothing you want to hear less than a strange noise coming from your AC.

Hissing noises aren’t uncommon, and many homeowners are surprised to find their air conditioner emitting this strange sound when they turn their thermostats down.

What does hissing in your AC mean? It could stem from several sources, including leaks and an unchanged filter.

Any foreign sound coming from your air conditioner is a call to action. When in doubt, always schedule air conditioner repair in Chicago, IL. But first, it might help to do some research and figure out what’s going on behind the scenes before you make the call.

Here are three of the most common reasons ACs start hissing.

1. A Refrigerant Leak

When the refrigerant line is punctured or develops an opening, it can cause a persistent hissing sound whenever you run your air conditioner. What you are hearing is gaseous refrigerant escaping the line.

While this is a problem in and of itself, there are a lot of consequences to a refrigerant leak you want to avoid, such as:

  • Reduced efficiency
  • Increased system strain and lowered cooling power
  • Higher energy bills
  • A frozen evaporator coil

Getting an HVAC professional to address the potential leak ASAP is the best way to avoid any excessive costs or damage to your unit.

2. A Clogged Air Filter

Luckily, this is the easiest and least expensive fix for a hissing AC. Air filters need to be changed regularly to prevent dirt and dust build-up in the unit. Some filters require a new replacement every 30 days, while others can last for 90 or more. This varies based on your indoor air quality and even your HVAC system use.

A clogged air filter makes it harder for air to flow through your AC. This can result in a telltale hissing that ultimately puts a strain on your air conditioner’s inner mechanisms. While the hissing may be off-putting, it is the least troublesome effect of a clogged filter.

Without being regularly cleaned and/or replaced, filters can cause build-up that leads to a host of AC woes. These can include motor breakdowns, furnace failure, frozen coils, and a spike in energy bills, all of which lead to poor performance.

Thankfully, this is an easy fix that can spare your system unnecessary strain and save you hundreds of dollars in repairs!

3. Leaking Ductwork

Ducts are built to last, but sometimes they run into issues. Ducts that are not properly sealed or weren’t installed properly are more likely to leak air when you run your AC. Leaking ductwork affects your home’s heating as well, so it’s a persistent problem you should address ASAP.

Some warning signs you have leaking ducts (along with hissing) include cold spots, higher bills, and warmer air despite setting your thermostat to cool.

Leaking ducts require a professional inspection and corrective strategy. This is a problem invisible to the naked eye, so an in-depth assessment and repair are crucial to saving you money and protecting your air conditioner’s health.

Contact the team at ServiceMax today for your next repair. We are here for you, 24/7.

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