Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be overlooked. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is heard from your ductwork, then you could have leaking air ducts. This is annoying, but not necessarily a reason to worry. 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 moments, you may not have any problems. That can be refrigerant in your expansion valve, which is part 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 paired with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak is present, you might notice a slight hissing sound as the refrigerant escapes through the leak. The coolant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, shut down the unit and call a expert HVAC company to come evaluate the noise.

If the problem 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 without repair, the leak will worsen. When it does, the hissing sound will often intensify, which can be a sign if you’re looking for a cause. You need to maintain adequate pressure in your system for it run as intended, and leaks create additional health and mechanical problems. You want to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is located in the exterior air conditioning unit, which is also called a condenser. Listen quietly for the hissing noise. If you find the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure in the compressor is too high. 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 costly parts to repair or replace inside an AC. Compressors are the part responsible for pushing refrigerant through the system. You cannot turn on an air conditioner and cool your home sans compressor. The expense changes based on factors like the type, unit size, and brand requirements. If you have a two stage compressor now, you will need to replace it with another two stage compressor. It’s impossible to upgrade or downgrade the compressor type - your unit has specific requirements for what components are installed and can’t be MacGyvered. While it’s impossible to say how much a compressor replacement is because of the variable costs, the receipt is frequently large enough to think about a replacement in older units. This is why it’s so important 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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