Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be ignored. Among the possible 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 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 stop after a few seconds?

If you hear a hissing noise that ends after a few seconds, you may not have any problems. That can be refrigerant in your expansion valve, which is a part of the normal 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 may indicate a refrigerant leak. If a refrigerant leak is present, you may hear a slight hissing sound as the refrigerant escapes through the leak. The coolant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, power down your HVAC and call a professional HVAC company to come take a look.

If the problem is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to help with the pressurization of the refrigerant gas and without repair, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a sign if you’re looking for the cause. You must maintain proper pressure in your HVAC system for it cool your home, and refrigerant leaks cause additional health and maintenance problems. You want 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. Listen around here for the hissing noise. If it turns out that the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure within the compressor is too high. 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 expensive parts to repair or replace inside an AC. Compressors are the part responsible for cycling refrigerant through the system. You cannot power on an HVAC system and cool your home sans compressor. The pricing is variable based on factors like the type, unit size, and brand requirements. If you have a two stage compressor now, you will need to replace it with a 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 provide estimates 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 crucial to shut off the air conditioning and call a trustworthy HVAC company if you hear hissing sounds coming from the compressor.

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