Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be ignored. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating from your air ducts, then you might have leaky air ducts. This is annoying, but not necessarily something to panic over. A hissing sound could 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 ends after a few moments, you may not have any problems. That could be refrigerant in your expansion valve, which is a part of the normal operation of your HVAC unit.

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound paired with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak presents itself, you may 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 have signs of a refrigerant leak, power down your HVAC and call a expert HVAC company to come take a look.

If the problem is a valve leak, it should be repaired by a professional as soon as possible. The job of the valves is to manage the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will increase, which can be a sign if you’re looking for a cause. You need to maintain adequate pressure in your system for it run as intended, and refrigerant leaks cause additional health and maintenance problems. You ought to get this fixed quickly 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 nearby the condenser for the hissing noise. If you find the compressor is the issue, this could be a dangerous situation because it is a sign that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, switch 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 AC unit. Compressors are the part responsible for pushing refrigerant through the system. You cannot turn on an air conditioner and cool your home sans compressor. The pricing changes based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, 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 components are installed in order to operate safely. While it’s impossible to provide estimates because of the variable costs, the bill is frequently high 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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