Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be overlooked. Among the potential causes are leaking5 refrigerant lines, an internal valve leak or a serious problem 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 may 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 ceases after a few seconds, you may not have any problems. That might 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 can indicate a refrigerant leak. If a refrigerant leak presents itself, you might hear a slight hissing sound as the refrigerant escapes from the leak. The coolant escapes as a gas and can be a worrisome health concern. If you see signs of a refrigerant leak, shut down the AC and call a qualified HVAC company to come take a look.

If the cause is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to regulate 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 a cause. You must maintain proper pressure in your system for it operate correctly, and refrigerant leaks cause additional health and mechanical problems. It’s best to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is located in the outdoor air conditioning unit, which is also called a condenser unit. Listen quietly for the hissing noise. If it turns out that the compressor is the problem, this could be a hazardous situation because it is a signal that the pressure in the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner immediately and call an HVAC 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 power on an HVAC system and cool your home without a compressor. The expense is variable based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you would need to replace it with a two stage compressor. It’s not possible 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 give a quote online because of the variable costs, the bill is frequently big enough to think about 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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