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 originating from your ductwork, then you could have leaky air ducts. This is annoying, but not necessarily something to panic over. A hissing sound could be a sign for any of these things, but we’ll try to narrow it down further.

Does the hissing sound end after a few seconds?

If you hear a hissing noise that stops after a few seconds, you may not have any problems. That can 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 may hear a light hissing sound as the refrigerant escapes via the leak. It escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, power down the unit and call a expert 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 left alone, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a signal if you’re looking for a cause. You must maintain adequate pressure in your system for it cool your home, 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 found in the outdoor air conditioning unit, which is also called a condenser. Listen quietly for the hissing noise. If it turns out that the compressor is the problem, this could be an unsafe situation because it is a signal that the pressure within the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, shut off your air conditioner immediately 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 air conditioner. Compressors are the part responsible for pushing refrigerant through the system. You cannot run an AC and cool your home without a compressor. The pricing varies based on factors such as 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 another two stage compressor. It’s impossible to upgrade or downgrade the compressor type - your unit has specific requirements for what parts are installed and can’t be MacGyvered. While it’s impossible to provide estimates because of the variable costs, the expense is often high enough to just do a replacement in older ACs. 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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