Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be disregarded. Among the possible causes are leaking5 refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is coming from your ductwork, then you could have leaking air ducts. This is annoying, but not necessarily something to panic over. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down a little further.

Does the hissing sound stop after a few seconds?

If you hear a hissing noise that ceases after a few moments, you may not have any problems. That could 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 along with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak develops, you may notice a slight hissing sound as the refrigerant escapes through the leak. The coolant escapes as a gas and can be a worrisome health concern. If you notice signs of a refrigerant leak, turn off the unit and call a expert HVAC company to come inspect the system.

If the issue is a valve leak, it should be repaired by a 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 often intensify, 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 maintenance problems. You want 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 a hazardous 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, turn off your air conditioner pronto and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive parts to repair or replace inside an air conditioner. Compressors are the part responsible for cycling refrigerant through the system. You cannot power on an HVAC system and cool your home without a compressor. The pricing changes based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you will 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 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 think about a replacement in older air conditioners. 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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