Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be overlooked. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is coming from your ducts, then you might have leaking 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 stop after a few seconds?

If you hear a hissing noise that stops after a few seconds, you may not have any issues. That can 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 is present, you may notice a light hissing sound as the refrigerant escapes from the leak. The coolant escapes as a gas and can be a major health concern. If you notice signs of a refrigerant leak, shut down the unit and call a qualified HVAC company to come evaluate the noise.

If the cause is a valve leak, it should be repaired by a professional 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 often intensify, which can be a sign if you’re looking for the cause. You need to maintain proper pressure in your HVAC 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 can be located in the exterior air conditioning unit, which is also called a condenser unit. Listen nearby the condenser for the hissing noise. If it turns out that the compressor is the issue, this could be an unsafe situation because it is an indication that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner without delay 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. Compressors are the part responsible for circulating refrigerant through the system. You cannot turn on an air conditioner 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 in your AC, 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 parts are installed and won’t accept substitutes. While it’s impossible to give a quote online because of the variable costs, the receipt is frequently large 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 trustworthy HVAC company if you hear hissing sounds coming from the compressor.