Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be ignored. Among the probable causes are leaking5 refrigerant lines, an internal valve leak or a serious failure 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 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 stop after a few seconds?

If you hear a hissing noise that stops after a few seconds, you may not have any problems. That might be refrigerant in your expansion valve, which is part and parcel 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 can indicate a refrigerant leak. If a refrigerant leak develops, you might notice a slight hissing sound as the refrigerant escapes via the leak. Refrigerant escapes as a gas and can be a worrisome health concern. If you notice signs of a refrigerant leak, turn off your HVAC and call a expert HVAC company to come take a look.

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 left alone, the leak will worsen. When it does, the hissing sound will increase, which can be a tell if you’re looking for a cause. You need to maintain adequate pressure in your HVAC system for it operate correctly, and leaks create additional health and mechanical problems. You ought to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be located in the outdoor air conditioning unit, which is also known as a condenser unit. Listen quietly for the hissing noise. If you find the compressor is the cause, this could be an unsafe 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, switch off your air conditioner without delay and call an expert 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 pushing refrigerant through the system. You cannot power on an HVAC system and cool your home without a compressor. The expense changes 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 can’t be MacGyvered. While it’s impossible to say how much a compressor replacement is because of the variable costs, the bill is often large enough to consider a replacement in older units. 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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