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 issue with your compressor. If the hissing noise is coming from your ducts, then you may have leaking air ducts. This is annoying, but not necessarily a reason to worry. A hissing sound may indicate any of these things, but we’ll try to narrow it down further.

Does the hissing sound cease after a few seconds?

If you hear a hissing noise that stops after a few moments, you may not have any issues. That could be refrigerant in your expansion valve, which is part of the normal operation of your HVAC unit.

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 presents itself, you may hear a slight hissing sound as the refrigerant escapes through the leak. It escapes as a gas and can be a major health concern. If you notice signs of a refrigerant leak, turn off 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 regulate the pressurization of the refrigerant gas and without repair, the leak will worsen. When it does, the hissing sound will increase, which can be a tell if you’re looking for the cause. You must maintain adequate pressure in your HVAC system for it operate correctly, and any leak will 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 located in the exterior air conditioning unit, which is also known as a condenser. Listen around here for the hissing noise. If the compressor is the problem, this could be a dangerous situation because it is an indication that the pressure inside the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner pronto and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive parts to repair or replace inside an AC. Compressors are the part responsible for circulating refrigerant through the system. You cannot power on an HVAC system and cool your home without a compressor. The expense varies based on factors like 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 compressors are installed and won’t accept substitutes. While it’s impossible to say how much a compressor replacement is because of the variable costs, the expense is often high enough to just do a replacement in older air conditioners. This is why it’s so important 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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