Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be overlooked. Among the possible causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is heard from your ducts, then you might have leaking air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound may indicate any of these things, but we’ll try to narrow it down a little more.

Does the hissing sound stop after a few seconds?

If you hear a hissing noise that ceases after a few seconds, you may not have any issues. That could be refrigerant in your expansion valve, which is part and parcel of the normal day to day operation of your HVAC system.

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak presents itself, you might hear a slight hissing sound as the refrigerant escapes via the leak. It escapes as a gas and can be a worrisome health concern. If you notice signs of a refrigerant leak, power down the AC and call a expert HVAC company to come take a look.

If the issue is a valve leak, it should be repaired by a technician as soon as possible. The job of the valves is to manage the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a tell if you’re looking for a cause. You must maintain adequate pressure in your system for it cool your home, and leaks create additional health and maintenance problems. You ought to get this fixed quickly if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is found in the exterior air conditioning unit, which is also known as a condenser. Listen quietly for the hissing noise. If it turns out that the compressor is the cause, this could be a hazardous situation because it is a signal that the pressure inside the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, shut off your air conditioner without delay and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey units to repair or replace inside an AC unit. Compressors are the part responsible for pushing refrigerant through the system. You cannot power on an HVAC system and cool your home without a compressor. The pricing is variable based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you will need to replace it with another two stage compressor. It’s not possible to upgrade or downgrade the compressor type - your unit has specific requirements for what components are installed in order to operate safely. While it’s impossible to say how much a compressor replacement is because of the variable costs, the expense is often high enough to think about a replacement in older ACs. This is why it’s critical to shut off the air conditioning and call a reputable HVAC company if you hear hissing sounds coming from the compressor.

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