Why is my AC making a hissing noise? 

A hissing noise inside your HVAC system should not be overlooked. Among the probable causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is originating from your air ducts, then you may have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down 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 issues. That can be refrigerant in your expansion valve, which is part 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 could indicate a refrigerant leak. If a refrigerant leak is present, you may notice a light 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 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 help with 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 the cause. You need to maintain adequate pressure in your system for it cool your home, and refrigerant leaks cause additional health and mechanical problems. You want to get this fixed post haste if possible. 

Are Hissing Noises Coming from the Compressor? 

The compressor can be found in the outdoor air conditioning unit, which is also called a condenser unit. 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 an indication that the pressure within the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner pronto and call a professional technician. 

Compressors are some of the most costly parts to repair or replace inside an AC unit. Compressors are the part responsible for circulating refrigerant through the system. You cannot run an AC and cool your home without a compressor. The expense changes based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor in your AC, 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 compressors 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 consider a replacement in older air conditioners. This is why it’s critical to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.