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 potential causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is heard from your ductwork, then you might have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound could indicate any of these things, but we’ll try to narrow it down a little further.

Does the hissing sound end after a few seconds?

If you hear a hissing noise that ends after a few seconds, you may not have any issues. That could be refrigerant in your expansion valve, which is a part of the normal 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 could indicate a refrigerant leak. If a refrigerant leak is present, you might hear a light hissing sound as the refrigerant escapes from the leak. It escapes as a gas and can be a worrisome health concern. If you see signs of a refrigerant leak, turn off your HVAC and call a professional HVAC company to come evaluate the noise.

If the cause is a valve leak, it should be repaired by a professional 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 the cause. You must maintain proper pressure in your system for it operate correctly, and refrigerant leaks cause additional health and maintenance problems. You ought to get this fixed quickly if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be located in the outdoor air conditioning unit, which is also called a condenser unit. Listen nearby the condenser for the hissing noise. If you find the compressor is the cause, this could be a hazardous situation because it is a signal that the pressure in the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner without delay and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey parts to repair or replace inside an air conditioner. Compressors are the part responsible for cycling refrigerant through the system. You cannot run an AC 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 would need to replace it with a two stage compressor. It’s impossible to upgrade or downgrade the compressor type - your unit has specific requirements for what parts are installed and won’t accept substitutes. While it’s impossible to provide estimates because of the variable costs, the bill is frequently high enough to just do a replacement in older air conditioners. This is why it’s crucial to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.

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