Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be disregarded. Among the possible causes are leaky 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 leaky air ducts. This is annoying, but not necessarily a reason to worry. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down a little further.

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 can be refrigerant in your expansion valve, which is part of the normal day to day operation of your HVAC mechanicals.

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound paired with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak presents itself, you may hear a slight hissing sound as the refrigerant escapes from the leak. Refrigerant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, power down the unit and call a expert HVAC company to come inspect the system.

If the issue 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 run as intended, and any leak will create additional health and maintenance problems. You ought to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is found in the exterior air conditioning unit, which is also called a condenser. Listen nearby the condenser for the hissing noise. If the compressor is the cause, this could be a dangerous situation because it is a sign that the pressure within the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner without delay and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly parts to repair or replace inside an AC unit. Compressors are the part responsible for circulating refrigerant through the system. You cannot turn on an air conditioner and cool your home sans compressor. The expense is variable based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, you would 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 compressors are installed in order to operate safely. While it’s impossible to give a quote online because of the variable costs, the receipt is often big enough to just do a replacement in older air conditioners. This is why it’s critical to shut off the air conditioning and call a trustworthy HVAC company if you hear hissing sounds coming from the compressor.

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