Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be disregarded. Among the possible causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is heard from your ductwork, then you could have leaky air ducts. This is annoying, but not necessarily a reason to worry. 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 problems. That could be refrigerant in your expansion valve, which is part and parcel 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 can indicate a refrigerant leak. If a refrigerant leak develops, you may hear a slight hissing sound as the refrigerant escapes from the leak. The coolant escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, shut down the AC and call a expert HVAC company to come evaluate the noise.

If the cause 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 tell if you’re looking for a cause. You must maintain adequate pressure in your system for it operate correctly, 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 located in the exterior air conditioning unit, which is also called a condenser. Listen nearby the condenser for the hissing noise. If you find the compressor is the issue, this could be a hazardous situation because it is a signal that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner pronto and call an expert 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 circulating refrigerant through the system. You cannot run an AC and cool your home sans compressor. The expense varies 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 a two stage compressor. It’s not possible 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 say how much a compressor replacement is because of the variable costs, the receipt is often large enough to consider a replacement in older air conditioners. This is why it’s crucial 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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