Heat Pump Noises: Common Causes and Fixes

HVAC Logo IconBy Tom MoorAugust 29, 2023

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Heat pump system

Is your heat pump emitting loud or unusual noises? These sounds often hold important clues. Aside from the sound of it starting or stopping a cycle or a gentle hum while operating, other heat pump noises should be inspected further as an issue is likely present.

Heat pump sounds rarely go away on their own; in fact, they tend to get worse over time if they’re left untreated. Keep reading as HVAC.com, your trusted source for heating, cooling, and indoor air quality advice, explains common heat pump system noises, what they mean, and how to fix them.

Heat Pump Noises Not to Worry About

All HVAC systems, including heat pumps, make some noise. A couple of noises that typically indicate everything is fine include:

  • Humming or Whirring. A gentle humming noise usually means your system – including the compressor and motor – is operating as it should. You may also hear a buzzing-type sound from the AC contactors and coils when electricity runs through them.
  • Clicking. Light-clicking noises are common when your heat pump system starts a cycle or shuts down. Clicking comes from components engaging and disengaging and isn’t usually a problem.

“Whirring or humming is typically the sound of the compressor and fans working together to circulate refrigerant and maintain temperature consistency,” said Rich Mullins, with H2O Plumbing in Corydon, IN. “Over the years, I've found that slight variations in these sounds are normal, but if you notice a sudden increase in volume or unusual patterns, it could indicate an issue with the compressor motor or fan blades. To address this, it’s essential to conduct regular maintenance, including cleaning the coils, checking for loose components, and lubricating moving parts.”

Heat Pump Noises to Worry About

While humming, buzzing, and clicking noises are normal during heat pump operation, some noises raise red flags. They include:

Hissing

The most common cause of a heat pump hissing noise is a refrigerant leak. As the refrigerant escapes through a small opening created by the leak, it transitions from a high-pressure liquid to a lower-pressure gas, resulting in a distinct hissing sound. Your heat pump won’t run efficiently or provide proper levels of heating and cooling when there’s a refrigerant leak, and a technician should be called immediately.

Rattling or Banging

Loose, displaced, or broken heat pump components can cause a rattling or banging sound when they make contact with other parts. Twigs and small rocks can also find their way into the outdoor condenser unit and become trapped in the fan blades or condenser coils, leading to disruptive heat pump noises.

Thumping or Knocking

An unbalanced, damaged, or malfunctioning fan or motor can cause thumping and knocking noises, leading to wear and tear. Depending on the extent of the damage, the fan or motor may need to be replaced.

“From my practical knowledge, I recommend shutting down the unit and visually inspecting the fan and motor assembly,” Mullins said. “If you notice any signs of wear or imbalance, it’s advisable to engage a qualified technician to address the issue promptly. Proper maintenance and occasional fan and motor replacement can prevent such noises from occurring.”

Gurgling or Bubbling

A heat pump gurgling sound is typically caused by the movement of refrigerant through the system, particularly when there’s an uneven flow or air trapped in the lines due to a refrigerant leak or low refrigerant levels. The aforementioned hissing noise may accompany a gurgling sound.

Squealing or Screeching

A worn-out fan motor belt within the heat pump’s motor or faulty bearings in the blower motor can lead to high-pitched noises such as squealing or screeching. Contacting a reputable HVAC technician to replace the belt at the first sign of issues can prevent further damage. These components might need replacement.

The Cost to Repair a Noisy Heat Pump

The cost of repairing a noisy heat pump can vary significantly based on the type of heat pump repair and the extent of the damage. On average, expect to pay $150 to $600 for heat pump repair, according to ThePricer.org. According to Andy Graham, an industry analyst with FIXR, you can expect to pay anywhere between $250 and $950 to repair a heat pump.

The Importance of Regular Heat Pump Maintenance

Regular heat pump maintenance plays a crucial role in preventing costly repairs. Scheduled maintenance, such as cleaning coils, inspecting electrical connections, and lubricating moving parts, ensures that components operate smoothly, reducing wear and tear. By addressing minor issues before they escalate and optimizing system efficiency, maintenance not only extends the lifespan of your heat pump but also minimizes the likelihood of sudden breakdowns, offering both peace of mind and long-term cost savings.

“Unusual noises should never be ignored,” said Kevin Price with Air Conditioning and Refrigeration in Tempe, AZ. “Have a trusted HVAC company inspect and resolve the problem promptly. Preventative maintenance is key for quiet, efficient heat pump operations.”


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