Why is my AC making a hissing noise? 

A hissing noise coming from your HVAC system should not be disregarded. Among the probable causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is coming from your ductwork, then you may 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 a little further. 

Does the hissing sound cease after a few seconds? 

If you hear a hissing noise that ends after a few moments, you may not have any problems. That could be refrigerant in your expansion valve, which is part of the normal day to day operation of your HVAC unit. 

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 might hear a slight hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a serious health concern. If you have signs of a refrigerant leak, shut down the unit and call a professional HVAC company to come evaluate the noise. 

If the problem 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 without repair, the leak will worsen. When it does, the hissing sound will increase, which can be a signal if you’re looking for the cause. You need to maintain proper pressure in your HVAC system for it run as intended, 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 exterior air conditioning unit, which is also known as a condenser. Listen around here for the hissing noise. If you find the compressor is the cause, this could be a dangerous situation because it is a sign 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 pronto and call an HVAC technician. 

Photo of AC unit showing location of compressor

Compressors are some of the most expensive parts to repair or replace inside an air conditioner. Compressors are the part responsible for pushing refrigerant through the system. You cannot turn on an air conditioner and cool your home without a compressor. The expense is variable based on factors such as 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 not possible to upgrade or downgrade the compressor type – your unit has specific requirements for what components are installed and can’t be MacGyvered. While it’s impossible to give a quote online because of the variable costs, the receipt is often big enough to think about a replacement in older units. 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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