AC Making Hissing Noises? Here’s Why

Is your AC making hissing noises?

If the hissing sound is periodic and lasts for several seconds, it could be the expansion valve. That’s not a major problem.

However, if the sound is sustained, you could be looking at more serious AC issues. And you do not want to ignore these.

We’ll take a look at the possible reasons your AC is hissing.

Refrigerant Leak

Refrigerant is a heat transfer fluid that’s stored in the thin copper tubes that run through your AC system. The refrigerant travels under high pressure, so if there’s a leak in any of the tubings, the escaping refrigerant will create a hissing sound. It may also be accompanied by a bubbling sound.

In more cases than not, a hissing air conditioner is the result of a refrigerant leak. Even though this is a common reason, it’s still a major problem. You will need to use an HVAC service to rectify it.

Along with the bubbling and hissing sounds, some of the tell-tale signs that you have a refrigerant leak are ice or frost on the refrigerant lines, warm air blowing from the vents, struggles with the system to cool the home, and/or higher energy bills.

Once you reach out to your HVAC service provider, be sure to inform them if you’ve witnessed any of these signs. You don’t want to delay getting this fixed. Otherwise, it could lead to damage to the compressor that will put the entire unit in jeopardy.

Speaking of the compressor…

Compressor Issues

It helps to be able to identify the source of the hissing. If you notice the hissing is coming from the compressor, it could be a leak in the compressor valve. This valve controls the pressurization of the refrigerant. So if it’s leaking, that means the HVAC system is creating pressure conditions that are unsafe for operation.

If the compressor used to hiss and is now screeching or shrieking, that’s a really bad sign. At that point, it’s usually more cost-effective to replace the AC system completely than replace an expensive compressor.

Bottom line, any time your compressor is making noises, it suggests that there are problems with the motor. Turn off your AC and call in a local technician immediately.

Leaking Ducts

Perhaps you’re noticing that the hissing sound is coming from the ducts. This happens when air is leaking somewhere. The echo chamber created by the ventilation system can accentuate this sound. You may also notice a more high-pitched whistle.

The hissing sounds are usually the result of air leaking because of improper sealing or the general age of your system. In this situation, you’ll notice higher energy bills.

While leaking ducts are not an immediate danger to your system, it would be wise to get an energy audit to determine if there is still a larger underlying problem.

Don’t Ignore Your AC Making Hissing Noises

Even if you think that your AC making hissing noises is merely the result of leaking ducts or an expansion valve, don’t take any chances.

Call out the professionals to give your system a comprehensive once-over. And soon enough, you’ll be relaxing in the cool comfort of your home without any worries.

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