Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be overlooked. Among the probable causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is coming from your ductwork, then you might have leaking air ducts. This is annoying, but not necessarily something to panic over. A hissing sound could indicate any of these things, but we’ll try to narrow it down further.

Does the hissing sound stop 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 along with a hissing sound? This can indicate a refrigerant leak. If a refrigerant leak is present, you may hear a light hissing sound as the refrigerant escapes via 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 AC and call a expert HVAC company to come evaluate the noise.

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 help with the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will increase, which can be a signal if you’re looking for a cause. You need to maintain proper pressure in your system for it run as intended, 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 can be 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 issue, this could be an unsafe situation because it is a signal that the pressure within 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 expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly units to repair or replace inside an AC unit. Compressors are the part responsible for cycling refrigerant through the system. You cannot turn on an air conditioner and cool your home sans compressor. The expense changes based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor in your AC, you would 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 give a quote online because of the variable costs, the bill is frequently high enough to consider a replacement in older air conditioners. 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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